Question

refer to the accompanying data set of mean​ drive-through service times at dinner in seconds at two fast food restaurants. construct a ​% confidence interval estimate of the mean​ drive-through service time for restaurant x at​ dinner; then do the same for restaurant y. compare the results.

Answer 1

Explanation:

Assuming the data is as shown, restaurant X has a mean service time of 180.56, with a standard deviation of 62.6.

The standard error is SE = s/√n = 62.6/√50 = 8.85.

At 95% confidence, the critical value is z = 1.960.

Therefore, the confidence interval is:

180.56 ± 1.960 × 8.85

180.56 ± 17.35

(163, 198)

Restaurant Y has a mean service time of 152.96, with a standard deviation of 49.2.

The standard error is SE = s/√n = 49.2/√50 = 6.96.

At 95% confidence, the critical value is z = 1.960.

Therefore, the confidence interval is:

152.96 ± 1.960 × 6.96

152.96 ± 13.64

(139, 167)