Population Standard Deviation

a. You are the manager of a popular retail store. You want to determine whether the population mean wait time for customer to

check-out has changed in the past month from its previous population mean value of 4.25 minutes. From past experience, you 

can assume that the population is normally distributed with a population standard deviation of 1.6 minutes. You select a sample 

of 43 customer’s wait time to check-out during a one hour period. The sample mean is 4.75 minutes. Determine whether there 

is evidence at the 0.05 level of significance that the population mean wait time to check-out has changed in the past month from 

its previous population mean value of 4.25 minutes. Explain your findings utlizing information from the hypothesis test you 

conduct. (5 pts.)

Qb. You are the manager of a fast-food restaurant. Based on a sample of two-hundred fifty drive-through orders, you discovered that 

orders were filled correctly 86.5% of the time. In an effort to improve the amount of orders filled correctly, you developed a new 

process to fill orders. After sampling two-hundred fifty orders under this new process, the results reviled that 225 orders were 

filled correctly. At the 0.01 level of significance, can you conclude that the new process population proportion of orders filled 

correctly is higher than the proportion of orders filled under the old process? Explain your findings utilizing information from the

test you conduct. (5 pts.)