Question

The arithmetic mean of ten boys is 8 years, 6 months one of them is 13 years old. Then the arithmetic mean of remaining 9 boys is

a)9.5 b) 9 c) 8 d) 7

Answer 1

The arithmetic mean of ten boys is 8 years, 6 months = 8.5 years
total age = 10* 8.5 = 85 years

one of them is 13 years
total age of rest = 85 - 13 = 72 years
mean of rest = 72/9 = 8 years

Answer is C) 8 years