Question

A set of five numbers with mean 10 and variance 2 is combined with a set of seven numbers with mean 12 and variance 2.5 .For the new set of numbers,find a)the mean b)the variance

Answer 1

A set of five numbers with a mean of 10 and variance 2 is combined with a set of seven numbers with a mean of 12 and a variance of 2.5. For the new set of numbers, find a) the mean b) the variance

Part a

Set 1 ------> 5 numbers

Set 2 ----> 7 numbers

total set=5+7=12 numbers

mean=(5*10+7*12)/12

mean=11.17

Part b

Variance=(5*2+7*2.5)/12

Variance=2.29