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CALCULATION OF AREA, SURFACE AREA AND VOLUME

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

<strong>CALCULATION</strong> <strong>OF</strong> <strong>AREA</strong>,<br />

<strong>SURFACE</strong> <strong>AREA</strong> <strong>AND</strong> <strong>VOLUME</strong><br />

SITAMS, Chittoor Page 1


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

A. Module Objective<br />

This Module describes various standard geometrical structures that exist and<br />

methods/formulas for calculating its characteristic values that can be used for various<br />

applications/calculations. The structures include circle, triangle, cylinder etc., that exists with<br />

in or as a shape, in all the practical entities we see in our daily life. So, calculating its area,<br />

Volume and perimeter gives the mathematical insight about the structure.<br />

For example, in order to determine the number of tiles of specific shape to be placed<br />

over the floor of specific dimension, area of both tile and the floor become the basis.<br />

B. Prerequisites (Related Formulas):-<br />

1. Area Calculations: Area is a quantity that expresses the extent of a twodimensional<br />

surface or shape in the plane. Area can be understood as the amount of<br />

material with a given thickness that would be necessary to fashion a model of the<br />

shape, or the amount of paint necessary to cover the surface with a single coat.<br />

1 square kilometer = 1,000,000 square meters,<br />

1 square meter = 10,000 square centimetres = 1,000,000 square millimeters<br />

1 square centimetre = 100 square millimeters<br />

1 square yard = 9 square feet<br />

1 square mile = 3,097,600 square yards = 27,878,400 square feet<br />

a. square = a 2<br />

b. rectangle = ab<br />

c. parallelogram = bh<br />

d. trapezoid = h/2 (b 1 + b 2 )<br />

e. circle = pi r 2<br />

f. ellipse = pi r 1 r 2<br />

SITAMS, Chittoor Page 2


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

g. triangle =<br />

h. equilateral triangle<br />

i. triangle given a,b,c = [s(s-a)(s-b)(s-c)] where<br />

s = (a+b+c)/2 (Heron's formula)<br />

j. isosceles triangle = (b/4)*(√(4a 2 -b 2 ))<br />

k. regular hexagon = (3√3/2)*a 2 where a is its side<br />

l. rhombus = 0.5*diagonal 1 * diagonal 2<br />

m.<br />

2. Volume Calculations: Volume is the quantity of threedimensional<br />

space enclosed by some closed boundary, for example, the space that<br />

a substance (solid, liquid, gas, or plasma) or shape occupies or contains. [1] Volume<br />

is often quantified numerically using the SI derived unit, the cubic metre.<br />

1 litre = (10 cm) 3 = 1000 cubic centimetres = 0.001 cubic metres,<br />

1 cubic metre = 1000 litres.<br />

Small amounts of liquid are often measured in millilitres,<br />

where 1 millilitre = 0.001 litres = 1 cubic centimetre.<br />

a. cube = a 3<br />

b. rectangular prism = a b c<br />

c. irregular prism = b h<br />

d. cylinder = b h = pi r 2 h<br />

e. pyramid = (1/3) b h<br />

SITAMS, Chittoor Page 3


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

f. cone = (1/3) b h = 1/3 pi r 2 h<br />

g. sphere = (4/3) pi r 3<br />

h. ellipsoid = (4/3) pi r 1 r 2 r 3<br />

3. Surface Area Calculations: Surface area is the measure of how much exposed<br />

area a solid object has, expressed in square units. Mathematical description of the<br />

surface area is considerably more involved than the definition of arc length of a<br />

curve.<br />

a. Surface Area of a Cube = 6 a 2 (a is the length of the side of<br />

each edge of the cube).<br />

In words, the surface area of a cube is the area of the six squares that<br />

cover it. The area of one of them is a*a, or a 2 . Since these are all the same,<br />

you can multiply one of them by six, so the surface area of a cube is 6 times<br />

one of the sides squared.<br />

b. Surface Area of a Rectangular Prism = 2ab + 2bc + 2ac<br />

(a, b, and c are the lengths of the 3 sides).<br />

In words, the surface area of a rectangular prism is the area of the six<br />

rectangles that cover it. But we don't have to figure out all six because we know<br />

that the top and bottom are the same, the front and back are the same, and the left<br />

and right sides are the same.<br />

The area of the top and bottom (side lengths a and c) = a*c. Since there are<br />

two of them, you get 2ac. The front and back have side lengths of b and c. The<br />

area of one of them is b*c, and there are two of them, so the surface area of those<br />

two is 2bc. The left and right side have side lengths of a and b, so the surface area<br />

of one of them is a*b. Again, there are two of them, so their combined surface<br />

area is 2ab.<br />

c. Surface Area of Any Prism (b is the shape of the ends)<br />

Surface Area = Lateral area + Area of two ends<br />

(Lateral area) = (perimeter of shape b) * L<br />

SITAMS, Chittoor Page 4


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Surface Area = (perimeter of shape b) * L+ 2*(Area of shape b)<br />

d. Surface Area of a Sphere = 4 pi r 2 (r is radius of circle)<br />

e. Surface Area of a Cylinder = 2 pi r 2 + 2 pi r h (h is the height<br />

of the cylinder, r is the radius of the top)<br />

Surface Area = Areas of top and bottom +Area of the side<br />

Surface Area = 2(Area of top) + (perimeter of top)* height<br />

Surface Area = 2(pi r 2 ) + (2 pi r)* h<br />

In words, the easiest way is to think of a can. The surface area is the areas of<br />

all the parts needed to cover the can. That's the top, the bottom, and the paper<br />

label that wraps around the middle. You can find the area of the top (or the<br />

bottom). That's the formula for area of a circle (pi r 2 ).<br />

Since there is both a top and a bottom, that gets multiplied by two. The side is<br />

like the label of the can. If you peel it off and lay it flat it will be a rectangle. The<br />

area of a rectangle is the product of the two sides. One side is the height of the<br />

can, the other side is the perimeter of the circle, since the label wraps once around<br />

the can.<br />

So the area of the rectangle is (2 pi r)* h. Add those two parts together and you<br />

have the formula for the surface area of a cylinder.<br />

4. Perimeter Calculations: A perimeter is a path that surrounds an area. The word<br />

comes from the Greek peri (around) and meter (measure). The term may be used<br />

either for the path or its length - it can be thought of as the length of the outline of<br />

a shape.<br />

a. square = 4a<br />

b. rectangle = 2a + 2b<br />

c. triangle = a + b + c<br />

d. circle = 2pi r<br />

circle = pi d (where d is the diameter). The perimeter of a circle is more<br />

commonly known as the circumference.<br />

SITAMS, Chittoor Page 5


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Properties of various Geometrical structures:<br />

a. Triangle<br />

In an equilateral triangle all sides have the same length. An equilateral triangle is also<br />

a regular polygon with all angles measuring 60°.<br />

In an isosceles triangle, two sides are equal in length. An isosceles triangle also has<br />

two angles of the same measure; namely, the angles opposite to the two sides of the same<br />

length; this fact is the content of the Isosceles triangle theorem.<br />

In a scalene triangle, all sides are unequal. The three angles are also all different in<br />

measure. Some (but not all) scalene triangles are also right triangles.<br />

A right triangle (or right-angled triangle, formerly called a rectangled triangle) has<br />

one of its interior angles measuring 90° (a right angle). The side opposite to the right angle is<br />

the hypotenuse; it is the longest side of the right triangle. The other two sides are called<br />

the legs of the triangle.<br />

Right triangles obey the Pythagorean theorem: the sum of the squares of the lengths of<br />

the two legs is equal to the square of the length of the hypotenuse: a 2 + b 2 = c 2 ,<br />

where a and b are the lengths of the legs and c is the length of the hypotenuse.<br />

Triangles that do not have an angle that measures 90° are called oblique triangles.<br />

A triangle that has all interior angles measuring less than 90° is an acute<br />

triangle or acute-angled triangle.<br />

A triangle that has one angle that measures more than 90° is an obtuse<br />

triangle or obtuse-angled triangle.<br />

A "triangle" with an interior angle of 180° (and collinear vertices) is degenerate.<br />

b. Quadrilateral<br />

In Euclidean plane geometry, a quadrilateral is a polygon with four sides (or 'edges')<br />

and four vertices or corners. Sometimes, the term quadrangle is used, by analogy<br />

with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-<br />

sided) and so on. The word quadrilateral is made of the wordsquad (meaning "four")<br />

and lateral (meaning "of sides").<br />

The diagonals of parallelogram bisect each other<br />

Each diagonal of a parallelogram divides it into two triangles of the same area<br />

The diagonals of rectangle are equal and bisect each other<br />

SITAMS, Chittoor Page 6


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

The diagonals of square are equal and bisect each other at right angles<br />

The diagonals of rhombus are unequal and bisect each other at right angles<br />

c. Circle<br />

The circle is the shape with the largest area for a given length of perimeter.<br />

A circle's circumference and radius are proportional.<br />

The area enclosed and the square of its radius are proportional.<br />

The constants of proportionality are 2π and π, respectively.<br />

The circle which is centered at the origin with radius 1 is called the unit circle.<br />

Some Important Metrics:<br />

1. 10,000 sq meters = 1 hectare<br />

2. 100 hectares = 1 sq kilo meter<br />

3. 1000 millimeters = 1 meter<br />

4. 100 centimeters = 1 meter<br />

5. 1000 metres = 1 kilometer<br />

6. 1000 kilograms = 1 mega gram or 1 tonne<br />

7. 3.6 kilometers per hour = 1 meter per second<br />

8. 3600 kilometers per hour = 1 kilometer per second<br />

C. Solved Examples<br />

1. The ratio between the length and the breadth of a rectangular park is 3 : 2. If a man cycling<br />

along the boundary of the park at the speed of 12 km/hr completes one round in 8 minutes,<br />

then the area of the park (in sq. m) is:<br />

A.15360 B.153600<br />

C.30720 D.307200<br />

Answer & Explanation<br />

Answer: Option B<br />

Explanation:<br />

Perimeter = Distance covered in 8 min. = 12000 x 8<br />

60 m = 1600 m.<br />

Let length = 3x metres and breadth = 2x metres.<br />

SITAMS, Chittoor Page 7


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Then, 2(3x + 2x) = 1600 or x = 160.<br />

Length = 480 m and Breadth = 320 m.<br />

Area = (480 x 320) m 2 = 153600 m 2 .<br />

2. An error 2% in excess is made while measuring the side of a square. The percentage of<br />

error in the calculated area of the square is:<br />

A.2%<br />

C.4%<br />

B.2.02%<br />

D.4.04%<br />

Answer & Explanation<br />

Answer: Option D<br />

Explanation:<br />

100 cm is read as 102 cm.<br />

A 1 = (100 x 100) cm 2 and A 2 (102 x 102) cm 2 .<br />

(A 2 - A 1 ) = [(102) 2 - (100) 2 ]<br />

= (102 + 100) x (102 - 100)<br />

= 404 cm 2 .<br />

404<br />

Percentage error = x 100 = 4.04%<br />

100 x 100 %<br />

3. The ratio between the perimeter and the breadth of a rectangle is 5 : 1. If the area of the<br />

rectangle is 216 sq. cm, what is the length of the rectangle?<br />

A.16 cm B.18 cm<br />

C.24 cm D.Data inadequate<br />

E.None of these<br />

Answer & Explanation<br />

Answer: Option B<br />

Explanation:<br />

2(l + b) =<br />

5<br />

b 1<br />

2l + 2b = 5b<br />

3b = 2l<br />

SITAMS, Chittoor Page 8


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

b = 2 l<br />

3<br />

Then, Area = 216 cm 2<br />

l x b = 216<br />

l x 2 l= 216<br />

3<br />

l 2 = 324<br />

l = 18 cm.<br />

4. The percentage increase in the area of a rectangle, if each of its sides is increased by 20%<br />

is:<br />

A.40%<br />

C.44%<br />

B.42%<br />

D.46%<br />

Answer & Explanation<br />

Answer: Option C<br />

Explanation:<br />

Let original length = x metres and original breadth = y metres.<br />

Original area = (xy) m 2 .<br />

New length = 120 x = 6 x<br />

100 m 5 m.<br />

New breadth = 120 y = 6 y<br />

100 m 5 m.<br />

New Area = 6 x x 6 y m<br />

2 = 36 xy<br />

5 5 25 m 2 .<br />

The difference between the original area = xy and new-area 36/25 xy is<br />

= (36/25)xy - xy<br />

= xy(36/25 - 1)<br />

= xy(11/25) or (11/25)xy<br />

xy<br />

Increase % = 11<br />

x 1 x 100 = 44%.<br />

%<br />

5. A rectangular park 60 m long and 40 m wide has two concrete crossroads running in the<br />

SITAMS, Chittoor Page 9


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

middle of the park and rest of the park has been used as a lawn. If the area of the lawn is<br />

2109 sq. m, then what is the width of the road?<br />

A.2.91 m<br />

B.3 m<br />

C.5.82 m<br />

D.None of these<br />

Answer & Explanation<br />

Answer: Option B<br />

Explanation:<br />

Area of the park = (60 x 40) m 2 = 2400 m 2 .<br />

Area of the lawn = 2109 m 2 .<br />

Area of the crossroads = (2400 - 2109) m 2 = 291 m 2 .<br />

Let the width of the road be x metres. Then,<br />

60x + 40x - x 2 = 291<br />

x 2 - 100x + 291 = 0<br />

(x - 97)(x - 3) = 0<br />

x = 3.<br />

6. The diagonal of the floor of a rectangular closet is 7 feet. The shorter side of the closet<br />

is 4<br />

feet. What is the area of the closet in square feet?<br />

A.5 1 B.13 1 4<br />

2<br />

C.27 D.37<br />

Answer & Explanation<br />

Answer: Option C<br />

Explanation:<br />

Other side= 15 2- 9 2ft<br />

2 2<br />

= 225 - 81 ft<br />

4 4<br />

= 144 ft<br />

4<br />

=6 ft.<br />

Area of closet = (6 x 4.5) sq. ft = 27 sq. ft.<br />

SITAMS, Chittoor Page 10


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

7. A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth.<br />

The percentage of decrease in area is:<br />

A.10%<br />

C.20%<br />

B.10.08%<br />

D.28%<br />

Answer & Explanation<br />

Answer: Option D<br />

Explanation:<br />

Let original length = x and original breadth = y.<br />

Decrease in area= xy -<br />

= xy - 18 xy<br />

25<br />

80 xx<br />

90 y<br />

100 100<br />

= 7 xy.<br />

25<br />

7 1<br />

Decrease % = xy x x 100 = 28%.<br />

25 xy %<br />

8. A man walked diagonally across a square lot. Approximately, what was the<br />

percent saved by not walking along the edges?<br />

Answer & Explanation<br />

Answer: Option C<br />

Explanation:<br />

Let the side of the square(ABCD) be x metres.<br />

Then, AB + BC = 2x metres.<br />

AC = 2x = (1.41x) m.<br />

Saving on 2x metres = (0.59x) m.<br />

SITAMS, Chittoor Page 11


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Saving % = 0.59xx 100 %<br />

= 30% (approx.)<br />

9. The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the<br />

rectangle must be:<br />

A.9 cm B.18 cm<br />

C.20 cm D.41 cm<br />

Answer & Explanation<br />

Answer: Option B<br />

Explanation:<br />

l 2 + b 2 = 41.<br />

Also, lb = 20.<br />

(l + b) 2 = (l 2 + b 2 ) + 2lb = 41 + 40 = 81<br />

(l + b) = 9.<br />

Perimeter = 2(l + b) = 18 cm.<br />

10. What is the least number of squares tiles required to pave the floor of a room 15 m 17 cm<br />

long and 9 m 2 cm broad?<br />

A.814 B.820<br />

C.840 D.844<br />

Answer & Explanation<br />

Answer: Option A<br />

Explanation:<br />

Length of largest tile = H.C.F. of 1517 cm and 902 cm = 41 cm.<br />

Area of each tile = (41 x 41) cm 2 .<br />

Required number of tiles = 1517 x 902 = 814.<br />

41 x 41<br />

11. The difference between the length and breadth of a rectangle is 23 m. If its perimeter<br />

is 206 m, then its area is:<br />

A.1520 m 2 B.2420 m 2<br />

C.2480 m 2 D.2520 m 2<br />

Answer & Explanation<br />

SITAMS, Chittoor Page 12


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Answer: Option D<br />

Explanation:<br />

We have: (l - b) = 23 and 2(l + b) = 206 or (l + b) = 103.<br />

Solving the two equations, we get: l = 63 and b = 40.<br />

Area = (l x b) = (63 x 40) m 2 = 2520 m 2 .<br />

12. The length of a rectangle is halved, while its breadth is tripled. What is the percentage<br />

change in area?<br />

A.25% increase<br />

C.50% decrease<br />

B.50% increase<br />

D.75% decrease<br />

Answer & Explanation<br />

Answer: Option B<br />

Explanation:<br />

Let original length = x and original breadth = y.<br />

Original area = xy.<br />

New length = x .<br />

2<br />

New breadth = 3y.<br />

New area = x x 3y = 3 xy.<br />

2 2<br />

Increase % = 1xy x1x 100 %<br />

= 50%.<br />

13. The length of a rectangular plot is 20 metres more than its breadth. If the cost of fencing<br />

the plot @ 26.50 per metre is Rs. 5300, what is the length of the plot in metres?<br />

A.40 B.50<br />

C.120 D.Data inadequate<br />

E.None of these<br />

Answer & Explanation<br />

Answer: Option E<br />

Explanation:<br />

SITAMS, Chittoor Page 13


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

Let breadth = x metres.<br />

Then, length = (x + 20) metres.<br />

Perimeter = 5300 m = 200 m.<br />

26.50<br />

2[(x + 20) + x] = 200<br />

2x + 20 = 100<br />

2x = 80<br />

x = 40.<br />

Hence, length = x + 20 = 60 m.<br />

14. A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If<br />

the area of the field is 680 sq. feet, how many feet of fencing will be required?<br />

A.34 B.40<br />

C.68 D.88<br />

Answer & Explanation<br />

Answer: Option D<br />

Explanation:<br />

We have: l = 20 ft and lb = 680 sq. ft.<br />

So, b = 34 ft.<br />

Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.<br />

15. A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom<br />

at 75 paise per sq. m, is:<br />

A.Rs. 456 B.Rs. 458<br />

C.Rs. 558 D.Rs. 568<br />

Answer & Explanation<br />

Answer: Option C<br />

Explanation:<br />

Area to be plastered= [2(l + b) x h] + (l x b)<br />

SITAMS, Chittoor Page 14


Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

= {[2(25 + 12) x 6] + (25 x 12)} m 2<br />

= (444 + 300) m 2<br />

= 744 m 2 .<br />

Cost of plastering = Rs. 744 x 75 = Rs. 558.<br />

100<br />

D. Exercise Problems<br />

1. A regular hexagon is inscribed in a circle of radius 8 cm. Find the area in circle other than<br />

hexagon portion<br />

a)6(2П -√3)<br />

b)3(2П -√3)<br />

c)18(2П -√3)<br />

d)none<br />

2. Find the area of a rhombus one side of which measures 15cm and one diagonal is 24cm?<br />

a)512 cm² b)216 cm²<br />

c)450 cm² d) 309 cm²<br />

3. Find the area of an isosceles triangle whose equal sides are 8cm each and the third side is<br />

10cm?<br />

a)10 cm² b)48 cm²<br />

c)5√39 cm²<br />

d)10√10 cm²<br />

4. A rope 88m long has been bent in the form of a circle. Find the area of the circle?<br />

a)343 m² b)616 m²<br />

c)196 m² d)225 m²<br />

5. The area of a circle is 220sq.cm.What will the area of a square inscribed in this circle will<br />

be?<br />

a)110 cm² b)120 cm²<br />

c)140 cm² d)160 cm²<br />

6. From a solid right circular cylinder with a height of 10cm and a diameter of the base of<br />

12cm,a right circular cone of the same height and base is cut off. Find the remaining volume<br />

of solid?<br />

a)624.6 cm 3 b)616 cm 3<br />

c)728.6 cm 3 d)754.28 cm 3<br />

7. A hollow spherical shell is made of metal of density 4.8g/ cm 3.<br />

If its internal and external radii are 10cm and 12cm respectively, find the weight of the shell<br />

a)15.24kg<br />

b)12.84kg<br />

c)14.64kg<br />

d)none<br />

8. If the average distance of the sun from the earth is 91 x 10 6 miles and the angles subtended<br />

by the sun at the edge of a person on the earth is 3 minutes, the diameter of the sun in miles is<br />

approximately<br />

a)85000 b)632000<br />

c)73333 d)793722<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

9. Ramu has bought a field in the shape of a parallelogram with a perimeter of 320m and one<br />

internal angle=150 0 .If he wants to utilize the maximum area for cultivation ,what should be<br />

the length of his field?<br />

a)70,90<br />

b)80,80<br />

c)75,85<br />

d)cannot be computed<br />

10. The front wheels of a cart cover a distance of 3П m in one revolution and the rear wheels<br />

cover a distance of 4Пm in one revolution.What will be the distance traveled by the cart<br />

when the front wheels have made 5 more revolution than the rear ones?<br />

a)20 b)15<br />

c)100 d)5<br />

11. A rectangular carpet has an area of 240 sq.metres.If its diagonal and the longer side<br />

together are equal to five times the shorter side,what will be the length of the carpet?<br />

a)5m<br />

b)10m<br />

c)12m<br />

d)24m<br />

12. If the ratio of the areas of two squares is 16:1, What will be the ratio of their perimeter?<br />

a)1:16<br />

b)1:4<br />

c)4:1<br />

d)8:1<br />

13. The length of a rectangle is 1 cm more than its breadth .its perimeter is 14cm.What will<br />

be the area of the rectangle?<br />

a)4 cm² b)3 cm²<br />

c)6 cm² d)12 cm²<br />

14. If the side of an equilateral triangle is decreased by 20%,its area is decreased by what<br />

percent?<br />

a)20%<br />

b)25%<br />

c)36%<br />

d)40%<br />

15. If the radius of a circle is doubled,by how much percentage does the area increases?<br />

a)100%<br />

b)200%<br />

c)300%<br />

d)400%<br />

16. Find the volume of a cube whose surface area is 384sq.cm?<br />

a)343 cm 3 b)384 cm 3<br />

c)400 cm 3 d)512 cm 3<br />

17. The slant height of the frustum of a cone is 20cm and the height of the frustum is 16cm<br />

.the radius of the smaller circle is 8cm.find the volume of the frustum?<br />

a)9880 cm 3 b)10459.43 cm 3<br />

c)11960 cm 3 d)12464 cm 3<br />

18. What is the total surface area of a cylinder that has been made from a rectangle of length<br />

12m & breadth 10m?<br />

a)120 m² b)132 m²<br />

c)120+25/П m²<br />

d)none<br />

19. Triangle ABC is right angled at C.What is the value of<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

tan A + tan B?<br />

a)a+b<br />

c)a²/bc<br />

b)c²/ab<br />

d)b²/ac<br />

20. A rectangle plot has to be fenced on one long side ,one short side and the diagonal.If the<br />

cost of fencing is Rs.5per metre ,the area of the plot is 1,200 sq.m. and the short side is 30m<br />

long,how much would be the job cost?<br />

a)Rs.300 b)400<br />

c)500 d)600<br />

21. A man walks at the rate of 6km/hr and crosses a square field diagonally in 9 seconds<br />

.What is the area of the field?<br />

a)81m²<br />

b)112.5m²<br />

c)121m²<br />

d)125m²<br />

22. The ratio of the length and breadth of a rectangular park is 3:2.A man cycles along the<br />

boundary of the park at a speed of 12km/hr and completes one round in 8min .find the area of<br />

the park.<br />

a)143200m²<br />

b)137900m²<br />

c)78300m²<br />

d)153600m²<br />

23. A room is 13m long ,9 m broad and 10m high .Find the cost of painting the four walls of<br />

the room at Rs.6 per.sq.m .The doors and windows occupy 32sq.m?<br />

a)Rs.1331 b)1225<br />

c)2448 d)3000<br />

24. A rectangular lawn 45m by 35m has two roads each 5m wide running in the middle of it,<br />

one parallel to length and the other parallel to the breadth. Find the cost of repairing them at<br />

rs.1 per sq.m?<br />

a)Rs.225 b)300<br />

c)375 d)400<br />

25. A field is in the form of a trapezium whose parallel sides are 110m and 65m and the<br />

height between the two parallel side is 56 am.Find the cost of ploughing the field at the rate<br />

of 70paise per sq.m?<br />

a)Rs.2250 b)1525<br />

c)3430 d)5120<br />

26. ABCD is a quadrilateral where in AC is 15cm . The length of the perpendicular from D<br />

and B on AC are 5cm and 7cm respectively.What will the area of the quadrilateral be?<br />

a)90cm²<br />

b)180cm²<br />

c)225cm²<br />

d)45cm²<br />

27. An equilateral triangle of side 6cm has its corners cut off to form a regular hexagon .What<br />

will be the area of the hexagon?<br />

a)9√3cm²<br />

b)6√3cm²<br />

c)3√3cm²<br />

d) √3cm²<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

28. A circular grassy land has a path 7m wide running round it on the outside. The radius of<br />

the land is 35m.how many stones of dimensions 20cm x 11cm are required to prove the path?<br />

a)7000 b)11000<br />

c)77000 d)10000<br />

29. The area of the circle circumscribed by a regular hexagon is 2П. What is the area of the<br />

hexagon?<br />

a)9√3cm²<br />

b)6√3cm²<br />

c)3√3cm²<br />

d) √3cm²<br />

30. The minute hand of a clock is 7cm long.What will the area swept by the minute hand in<br />

15minutes be?<br />

a)19.25 cm²<br />

b)38.5 cm²<br />

c)77 cm² d)none<br />

31. A powder tin has a square base with sides of 8cm and height 14cm.another powder tin has<br />

a circular base with a diameter of 8cm and height 14cm.find the difference in their capacities?<br />

a)9√3cm²<br />

c)3√3cm²<br />

b)6√3cm²<br />

d) None<br />

32. A large field of 700 hectares is divided in to two parts. The difference of the areas of the<br />

two parts in one-fifth of the average of the two areas. What is the area of the smaller part in<br />

hectages?<br />

a)225 b)280<br />

c)300 d)315<br />

33. A rectangular paper, when folded into two congruent parts had a perimeter of 34 cm for<br />

each part folded along one set of sides and the same in 38 cm when folded along the other set<br />

of sides. What is the area of the paper in sq. cm<br />

a)140 b)240<br />

c)540 d)None<br />

34. The cost of carpeting a room 18m long with a carpet 75 cm wide at Rs. 4.50 per metre is<br />

Rs. 810. The breadth of the room is___mts.<br />

a)7 b)7.5<br />

c)8 d)8.5<br />

35. A courtyard 25 cm long and 16 mts broad is to be paved with bricks of dimensions 20 cm<br />

by 10 cm. The total number of bricks required is<br />

a)18000 b)20000<br />

c)25000 d)None<br />

36. The length of a rectangle is 20% more than its breadth. What will be the ratio of the area<br />

of a rectangle to that of a square whose side is equal to the breadth of the rectangle.<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

a)2:1<br />

c)6:5<br />

b)5:6<br />

d)None<br />

37. A square and rectangle have equal areas. If their perimeters are p 1 and p 2 respectively,<br />

then<br />

a)p 1 p 2 d)None<br />

38. The diagonal of a square is 4√2 cm. The diagonal of another square whose area is double<br />

that of the first square is ___ cm.<br />

a)8 b) 8√2<br />

c) 4√2 d)16<br />

39. A rectangular water tank is 80m X 40 m. Water flows into it through a pipe 40 sq.cm at<br />

the opening at a speed of 10 km/hr. By how much, the water level will rise in the tank in half<br />

an hour<br />

a)3/2 cm<br />

c)5/8 cm<br />

b)4/9 cm<br />

d)None<br />

40. A hall is 15 m long and 12 m broad. If the sum of the areas of the floor and the ceiling is<br />

equal to the sum of areas of the four walls, the volume of the hall is<br />

a)720 b)900<br />

c)1200 d)1800<br />

41. The sum of the length, breadth and depth of a cuboid is 19 cm and its diagonal is 5√5 cm.<br />

Its surface area is___ sq. cm<br />

a)125 b)236<br />

c)361 d)486<br />

42. What is the number of iron rods, each of length 7 mts and diameter 2 cm that can be made<br />

out of 0.88 cubic metres of iron<br />

a)100 b)200<br />

c)300 d)400<br />

43. A swimming pool 9 m wide and 12 m long is 1 m deep on the shallow side and 4 m deep<br />

on the deeper side. Its volume is___ mt. cube<br />

a)208 b)270<br />

c)360 d)408<br />

44. The ratio of total surface area to lateral surface area of a cylinder whose radius is 20 cm<br />

and height 60 cm is<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

a)2:1<br />

c)4:3<br />

b)3:2<br />

d)5:3<br />

45. A powder tin has a square base with side 8 cm and height 14 cm. Another tin has a<br />

circular base with diameter 8 cm and height 14 cm. The difference in their capacities is___<br />

cu.cms<br />

a)0 b)132<br />

c)137.1 d)192<br />

46. The ratio between the radius of the base and the height of a cylinder is 2:3. If its volume<br />

is 12936 cu. Cm, the total surface area of the cylinder is____sq.cm<br />

a)2587.2 b)3080<br />

c)25872 d)38808<br />

47. The radius of the cylinder is half its height and area of the inner part is 616 sq.cm.<br />

Approximately how many litres of milk can it contain<br />

a)1.4<br />

c)1.7<br />

b)1.5<br />

d)1.9<br />

48. The sum of the radius of the base and height of a solid cylinder is 37 metres. If the total<br />

surface area of the cylinder be 1628 sq.metres, it volume is<br />

a)3180 b)4620<br />

c)5240 d)None<br />

49. Two cones have their heights in the ratio 1:3 and radii 3:1. The ratio of their volumes is<br />

a)1:1<br />

c)3:1<br />

b)1:3<br />

d)2:3<br />

50. The radii of two cones are in ratio 2:1, their volumes are equal. Find the ratio of their<br />

heights<br />

a)1:8<br />

c)2:1<br />

b)1:4<br />

d)4:1<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

SOLUTION TO EXERCISE PROBLEMS:<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

E. Previous Exam Questions:<br />

1.If the volume of a sphere is divided by its surface area, the result is 27 cm. The radius of the<br />

sphere is___cm. [C.D.S. 2005]<br />

a)9 cm b)36 cm<br />

c)54 cm d)81 cm<br />

2. Spheres A and B have their radii 40 cm and 10 cm respectively. The ratio of the surface<br />

area of A to the surface area of B is: [Bank P.O. 2000]<br />

a)1:4<br />

c)4:1<br />

b)1:16<br />

d)16:1<br />

3. Surface area of a sphere is 2464 sq. cm. If its radius be doubled, then the surface are of the<br />

new sphere will be [Bank P.O. 2001]<br />

a)20 b)15<br />

c)100 d)5<br />

4.If the radius of a sphere is doubled, how many times does its volume become<br />

[S.S.C. 2000]<br />

a)2 times b)4 times<br />

c)6 times d)8 times<br />

5.If the radius of a sphere is increased by 2 cm, then it surface area increases by 352 sq. cm.<br />

The radius of the sphere before the increase was___ cm.<br />

[C.D.S.<br />

2006]<br />

a)3 b)4<br />

c)5 d)6<br />

6.If the measured value of the radius is 1.5% larger, the percentage error (correct to one<br />

decimer place) made in calculating the volume of a sphere is<br />

[Bank P.O. 2003]<br />

a)2.1<br />

c)4.6<br />

b)3.2<br />

d)5.4<br />

7.A cylindrical vessel of radius 4 cm contains water. A solid sphere of radius 3 cm is lowered<br />

in to the water until it is completely immersed. The water level in the vessel will rise<br />

by___cm.<br />

[Infosys 2009]<br />

a)2/9<br />

b)4/9<br />

c)9/4<br />

d)9/2<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

8.12 spheres of the same size are made from melting a solid cylinder of 16 cm diameter and<br />

2 cm height. The diameter of each sphere is___cm. [C.D.S. 2009]<br />

a)√3 b)2<br />

c)3 d)4<br />

9.A cylinder tub of radius 12 cm contains water upto a depth of 20cm. A spherical iron ball is<br />

dropped into the tub and thus the level of water is raised by 6.75 cm. The radius of the ball<br />

is__cm. [C.D.S. 2010]<br />

a)4.5 b)6<br />

c)7.25 d)9<br />

10.The length of a rectangle is halved, while its breadth is tripled. What is the percentange<br />

change in area [Bank P.O. 2005]<br />

a)25% increase<br />

c)50% decrease<br />

b)50% increase<br />

d)75% decrease<br />

11.The length of rectangle is decreased by r% and breadth is increased by (r+5)%. Find r, if<br />

area of triangle is unaltered. [Bank P.O. 2000]<br />

a)5 b)8<br />

c)10 d)15<br />

12.The length of a rectangle is increased by 60%. By what percent would the width have to<br />

be decreased so as to maintain the same area [C.D.S. 2011]<br />

a)75/2 %<br />

c)75%<br />

b)60%<br />

d)120%<br />

13. The perimeters of five squares are 24 cm, 32 cm 40 cm, 76 cm and 80 cm respectively.<br />

The perimeter of another square equal in area to the sum of the areas of these squares<br />

is___cm.<br />

[S.S.C. 2003]<br />

a)31 b)62<br />

c)124 d)961<br />

14.The number of marble slabe of size 20cm X 30cm required to pave the floor of a square<br />

room of side 3 mt is<br />

[Bank P.O.<br />

2010]<br />

a)100 b)150<br />

c)225 d)250<br />

15. 50 square stone slabs of equal size were needed to cover a floor area of 72 sq.cm. The<br />

length of each stone slabe is___cm.<br />

[C.D.S.<br />

2008]<br />

a)102 b)120<br />

c)201 d)210<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

16.A rectangular room can be partitioned in to two equal square rooms by a partition 7 metres<br />

long. What is the area of the rectangular room in square metres [Bank P.O. 2005]<br />

a)49 b)147<br />

c)196 d)None<br />

17.The three sides of a triangle are 5cm, 12cm and 13 cm respectively. Then, its area<br />

is___sq.cm<br />

[S.S.C. 2000]<br />

a)10√3<br />

b)10√6<br />

c)20 d)30<br />

18.The sides of a triangle are in the ratio of ½, 1/3, 1/4 . If the perimeter is 52 cm. Then the<br />

length of the smallest side is____cm. [Bank P.O. 2004]<br />

a)9 b)10<br />

c)11 d)12<br />

19.The area of a triangle is 216 sq.cm and its sides are in the ratio 3:4:5. The perimeter of the<br />

triangle is___cm. [C.D.S. 2007]<br />

a)49 b)12<br />

c)35 d)72<br />

20.The sides of a triangle are 3cm, 4 cm, and 5 cm. The area of the triangle formed by joining<br />

the mid-points of the sides of this triangle is [C.D.S. 2006]<br />

a)3/4<br />

b)3/2<br />

c)3 d)6<br />

21. The slant height of a right circular cone is 10 mts and its height is 8 mts . Find the area of<br />

its curved surface____sq.mts. [Bank P.O. 2005]<br />

a)30π<br />

c)60π<br />

b)40π<br />

d)80π<br />

22. If a right circular cone of height 24 cm has a volume of 1232 cu.cm, then the area of its<br />

curved surface is___sq.cm [S.S.C. 2008]<br />

a)154 b)550<br />

c)704 d)1254<br />

23.The curved surface of a right circular cone of height 15 cm and base diameter 16 cm<br />

is___sq.cm [S.S.C. 2002]<br />

a)60π<br />

c)120π<br />

b)68π<br />

d)136π<br />

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Aptitude and Reasoning Course<br />

Volume<br />

Area, Surface area and<br />

24. If the volume of a sphere is divided by its surface area, the result is 27 cm. The radius of<br />

the sphere is____cm. [C.D.S. 2005]<br />

a)9 b)36<br />

c)54 d)81<br />

25. If the radius of a sphere is doubled, how many times does its volume become___times.<br />

[S.S.C. 2005]<br />

a)2 b)4<br />

c)6 d)8<br />

26. If the radius of a sphere is increased by 2 cm, then its surface area increases by 352<br />

sq.cm. The radius of the sphere before the increase was___cm.<br />

[R.R.B.<br />

2003]<br />

a)3 b)4<br />

c)5 d)6<br />

27. There is a square of side 6 cm . A circle is inscribed inside the square. Find the ratio of<br />

the area of circle to square. [Honey Well<br />

2009]<br />

a) π/5 b) π/4<br />

c) π/6 d) π/2<br />

28. One rectangular plate with length 8inches,breadth 11 inches and 2 inches thickness is<br />

there. What is the length of the circular rod with diameter 8 inches and equal to<br />

volume of rectangular plate?<br />

[HCL<br />

2010]<br />

a)3.5<br />

b)4.5<br />

c)5.5<br />

d)6.5<br />

29. If the length of the rectangle is reduced by 20% and breath is increased by 20 % what is<br />

the net change in % [TCS 2010]<br />

a)3 b)4<br />

c)5 d)6<br />

30. How many squares with sides 1/2 inch long are needed to cover a rectangle that is 4 feet<br />

long & 6feet wide<br />

[Infosys<br />

2010]<br />

a) 24 b)96<br />

c)3456 d)13824<br />

31. A warehouse had a square floor with area 10,000 sq.meters. A rectangular addition was<br />

built along one entire side of the warehouse that increased the floor by one-half as much as<br />

the original floor. How many meters did the addition extend beyond the original buildings?<br />

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Aptitude and Reasoning Course<br />

Volume<br />

A)10 B)20<br />

C)50 D)200<br />

Area, Surface area and<br />

[TCS 2011]<br />

32. A rectangular tank 10" by 8" by 4" is filled with water. If all of the water is to be<br />

transferred to cube-shaped tanks, each one 3 inches on a side, how many of these smaller<br />

tanks are needed?<br />

A. 9 B. 12 [Infosys 2011]<br />

C. 16 D. 21<br />

Key to Exercise Problems:-<br />

1.d 2.b 3.c 4.b 5.c 6.d 7.c 8.d 9.b 10.a<br />

11.d 12.c 13.d 14.c 15.c 16.d 17.b 18.d 19.b 20.d<br />

21.b 22.d 23.c 24.c 25.c 26.a 27.b 28.c 29.c 30.b<br />

31.a 32.d 33.a 34.a 35.b 36.c 37.a 38.a 39.c 40.c<br />

41.b 42.d 43.b 44.c 45.d 46.b 47.b 48.b 49.c 50.b<br />

Key to Previous Exam Questions:-<br />

1.d 2.d 3.b 4.d 5.d 6.c 7.c 8.d 9.d 10.b<br />

11.e 12.a 13.c 14.c 15.b 16.d 17.d 18.d 19.d 20.b<br />

21.c 22.b 23.d 24.c 25.d 26.d 27.b 28.a 29.b 30.a<br />

31.c 32.b<br />

SITAMS, Chittoor Page 35

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