A supermarket is interested in finding out wheather the mean

A supermarket is interested in finding out wheather the mean weekly sales volume of Coca-Cola are the same when the softdrinks are displayed on the top shelf and when they are displayed on the bottom shelf. 10 stores are randomly selected from the supermaket chain with 5 stores using the top shelf display and 5 stores using the bottom shelf display. Assume that the samples are normally distributed with equal population variances. Refere to the sales volume data in the table below, Top shelf Sales Mean=41.6, Variance=249.84, Bottom shelf sales Mean=62.2, Variance=66.96.

What is the sample pooled variance S_p²?

    a. 158.4
    b. 11.995
    c. 0
    d. -11.995

Solution

Here,

Sp^2 = (s1^2 + s2^2)/2

= (249.84 + 66.96)/2

= 158.4 [ANSWER, A]