Veto q&a 7 Month22 (1)

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Q There are 30 students in a class. One student weighing
25 kg goes away and a new student joins the
class. If the average weight is then increased by
200 grams. what is the weight of new student?
a) 32 kg b) 31 kg c) 30 kg d) 29 kg
A : b) 31 kg
Weight of the student goes away + (number of
students x increase in average)
⎛ 1⎞
25 + ⎜30 × ⎟
⎝ 5 ⎠
25 + 6 = 31 kg
Q There are 24 boys and 16 girls in a class. For a class
test the average marks of boys is 25 and that of girls
is 24. The average mark of the total students in that
class is?
a) 24.6 b) 26.4 c) 24.5 d) 24.8
A : a) 24.6
Total mark = Average x number
Total mark of boys = 24 x 25 = 600
Total mark of girls = 16 x 24 = 384
Total mark = 600 + 384 = 984
Total students = 24 + 16 = 40
Average mark = Total mark
Total students
984
= = 24.6
40
Q Out of the five numbers, average of first four numbers
is 15 and the average of last four numbers is 12. Also
last number is 18. What is the first number?
a) 48 b) 27 c) 33 d) 30
A : d) 30
Average of first 4 number = 15
Total of first 4 number = 15 x 4 = 60
Average of last 4 number = 12
Total of last 4 number = 12 x 4 = 48
It is given that last number = 18
Total of 5 number = 60 + 18 =78
∴The first number = 78 - 48 = 30
Q The average age of 15 persons is 24 years. Later
a boy is included into this group then the average
becomes 23 years. The age of the boy will be?
a) 22 b) 8 c) 18 d) 12
A : b) 8
Previous Average + (number of members x increase
in average)
Here the average become 24 to 23
So the increasement of average = -1
Number of members = 15 + 1 = 16
∴age of the boy = 24 + (16 x -1)
= 24 - 16 = 8
Q The average height of a group of five students was
165 cm. One student of height 160 cm left the group.
After two years, the height of the remaining students
increases by 2cm, 3cm, 2cm and 4cm. The new
mean height is?
a) 135.2cm b) 169cm c) 169.5cm d) 160cm
A : b) 169cm
Total height = Average x number of students
= 165 x 5 = 825
After the 160cm height student goes away
Total height = 825 - 160 = 665
After 2 years total height = 665 + (2+3+2+4)
= 676
Average height = Total height
number of students
676
= = 169cm
4
Q Average of 5 consecutives odd numbers A, B, C, D
and E is 45. What is the product of B and D?
a)2025 b) 1935 c) 2021 d) 1981
A : c) 2021
If the average of ‘n’ consecutive odd number is A
then the largest number = A + (n - 1)
Here, n = 5, A = 45
Largest number,
E = 45 + (5 - 1) = 49
∴D = 49 - 2 = 47
C = 47 - 2 = 45
B = 45 - 2 = 43
B x D = 43 x 47 = 2021
Q The middle number among 11 consecutive natural
number is 28. Find the sum of 11 numbers?
a) 308 b) 380 c) 318 d) 320
A : a) 308
Sum = 11 x 28 = 308
Q&A Bonus
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