Math-Book-GMAT-Club

cm?
A) 324
B) 729
C) 243
D) 324
E) 729
Solution:
Answer (d)
Example 3 : A cube of side 5cm is painted on all its side. If it is sliced into 1 cubic centime cubes, how many 1
cubic centimeter cubes will have exactly one of their sides painted?
A. 9
B. 61
C. 98
D. 54
E. 64
Solution: Notice that the new cubes will be each of side 1Cm. So on any face of the old cube there will be 5x5=25
of the smaller cubes. Of these, any smaller cube on the edge of the face will have 2 faces painted (one for every
face shared with the bigger cube). The number of cubes that have exactly one face painted are all except the ones
on the edges. Number on the edges are 16, so 9 per face.
There are 6 faces, hence 6*9=54 smaller cubes with just one face painted.
Answer is (d)
Example 4 : What is the surface area of the cuboid C ?
(1) The length of the diagonal of C is 5
(2) The sum of the sides of C is 10
Solution: Let the sides of cuboid C be
We know that the surface area is given be
(1) : Diagonal = . Not sufficient to know the area
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