I need help with this question.

The amount of time a bank teller spends with each customer has a population mean, u, of 3.10 minutes and a standard deviation, o, of 0.40 minute. Complete parts (a)through (d)a. If you select a random sample of 16 customers, what is the probability that the mean time spent per customer is at least 2.9 minutes?(Round to four decimal places as needed.)b. If you select a random sample of 16 customers, there is an 83% chance that the sample mean is less than how many minutes?(Round to four decimal places as needed.)c. What assumption must you make in order to solve (a) and (b)?O A. That the population is normally distributedO B. That the sample is symmetrically distributed and such that the Central Limit Theorem will likely holdO C. That the population is symmetrically distributed and such that the Central Limit Theorem will likely hold for samples of size 16D. That the population is uniformly distributedd. If you select a random sample of 100 customers, there is an 83% chance that the sample mean is less than how many minutes?(Round to four decimal places as needed.)