iQ2 In a study about childrens pocket money two samples of s

iQ2

In a study about children?s pocket money, two samples of schoolchildren were asked how much money they received each week. In one sample, of size 80, the mean is ?6.65. In the other sample, of size 41, the mean is pound 8.21. Calculate the mean based on the combined sample. Give your answer correct to two decimal places. (Do NOT include the pound sign in your answer.)

Solution

n1=80    x1=6.65

n2=41      x2=8.21

combined mean = (n1*x1+n2*x2)/( n1+n2)

=( 80*6.65+41*8.21) /( 80+41)

=868.61/121

=7.1785

Combined mean =7.18     ( two decimals)