Average

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In a family, the average age of a father and a mother is 35 years. The average age of the father, mother and their only son is 27 years. What is the age of the son?
12 years
no
11 years
yes
10.5 years
no
10 years
no
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The average of eight numbers is 20. If the sum of first two numbers is 31, the average of the next three numbers is 21 1/3 and the Seventh and eighth numbers exceed the sixth number by 4 and 7 respectively, then the eighth number is....
20
no
25
yes
21.6
no
25.3
no
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The average of the first 100 positive integers is....
100
no
51
no
50.5
yes
49.5
no
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The average age of 4 boys, five year ago was 9 years. On including a new boy, the present average age of all the five is 15 years. The present age of the new boy is....
14 years
no
6 years
no
15 years
no
19 years
yes
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If the average of 39, 48, 51, 63, 75, 83, x and 69 is 60, then the value of x is....
52
yes
53
no
50
no
51
no
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A man’s pension on retirement from service is equal to half the average salary during last 3 years of his service. His salary from 1-1-1983 is Rs. 380 per month with increment of Rs. 40 due on 1-10-83, 1-10-84 and 1-10-85, if he retires on 1-1-86, what pension does he draw?       
Rs. 205
no
Rs. 215
yes
Rs. 225
no
Rs. 230
no
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The average weight of a group of 20 boys was calculated to be 89.4 kg and it was later discovered that one weight was misread as 78kg instead of 87 kg. The correct average weight is....
88.95 kg
no
89.25 kg
no
89.55 kg
no
89.85 Kg
yes
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If a, b, c, d, e are five consecutive odd numbers, their average is....
A + 4
yes
5 (a + 4)
no
Abcde / 4
no
5 (a + b + c + d + e)
no
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If out of 10 selected students for an examination, 3 were of 20 years age, 4 of 21 and 3 of 22 years, the average age of the group is....
20 years
no
22 years
no
21 years
yes
21.5 years
no
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The average of 11 numbers is 63. If the average of first six numbers is 60 and the last six numbers is 65 then the 6th numbers is....
57
yes
60
no
62
no
64
no
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