Question

A local pizza place claims that they average a delivery time of 7.32 minutes. To test this claim, you order 11 pizzas over the next month at random times on random days of the week. You calculate the average delivery time and sample standard deviation from the 11 delivery times (minutes), and with the sample mean and sample standard deviation of the time (minutes), you create a 95% confidence interval of (7.648, 9.992). (delivery time is normally distributed)

a. What is the sample mean of 11 delivery times?

b. What is the sample standard deviation of 11 delivery times?

c. Mary wants to know whether the actual average delivery time is greater than local pizza place’s claim, 7.32 minutes. Based on the sample data of 11 times, she wants to do hypotheses testing with 5% significance level. (Use sample mean and sample standard deviation obtained in a and b.)

i. State the null and alternative hypotheses.

ii. Calculate test statistics.

iii. Obtain p-value or rejection region.

iv. Make conclusion.

Answer 1