Question

Suppose a chain restaraunt has run a major advertising campaign in the hopes of increasing monthly sales. To investigate the effectiveness of this​ campaign, the restaraunt randomly selected six different locations and recorded the monthly sales before and after the advertising. The accompanying data represents these sales figures in thousands of dollars. Assume Population 1 is defined as sales after the advertising campaign and Population 2 is defined as sales before the advertising campaign. Which one of the following statements is​ true?

Restaruant 1 2 3 4 5 6

After $123 $122 $145 $156 $160 $134

Before $107 $110 $143 $168 $145 $125

A.

Because the​ 90% confidence interval does not include​ zero, we cannot conclude that the average restaurant sales per month after the advertising campaign are higher than the average restaurant sales per month before the advertising campaign.

B.

Because the​ 90% confidence interval includes​ zero, we cannot conclude that the average restaurant sales per month after the advertising campaign are higher than the average restaurant sales per month before the advertising campaign.

C.

Because the​ 90% confidence interval includes​ zero, we can conclude that the average restaurant sales per month after the advertising campaign are lower than the average restaurant sales per month before the advertising campaign.

D.

Because the​ 90% confidence interval does not include​ zero, we can conclude that the average restaurant sales per month after the advertising campaign are higher than the average restaurant sales per month before the advertising campaign.

Answer 1

After	Before	After - Before
123	107	16
122	110	12
145	143	2
156	168	-12
160	145	15
134	125	9

Here

sample mean of difference

sample standard deviation of difference

and sample size n = 6

a 90% confidence interval for the mean difference

ans-> B) Because the​ 90% confidence interval includes​ zero, we cannot conclude that the average restaurant sales per month after the advertising campaign are higher than the average restaurant sales per month before the advertising campaign.