help plzzzz

A national grocer's magazine reports the typical shopper spends eight minutes in line waiting for checkout. A sample of 24 shoppers at the local Miracle Mart showed a mean of 7.5 minutes with a standard deviation of 3.2 minutes. Is the waiting time at the local Miracle Mart less than the national average? Use a 0.05 significance level to determine your answer. Explain.

q2)Back to our convenience store in Zap, ND. Let's assume your friend says that the average sale of all her customers is $23.00. Your friend does not know the standard deviation of the population of sales. (I guess that is why she hired you as her consultant.) You setup a random sampling technique whereby you ask your friend to randomly sample 50 customers in a particular month. Your friend reports that her sample of 50 customers had an average purchase of $25.00. Is this reasonable? In other words, what is the likelihood of this occurring? You will need to know the standard deviation of the sample... assume you calculated it and it was $3.00. Your friend wants to know if this was a true (reasonable) sampling of her customers. What do you tell her? Can you deduce if her business is increasing?