The amount of time a bank teller spends with each customer has a population mean 3.10 minutes and standard deviation 0.40 minutes. Assuming that this is a normal population, find:
a. What is the probability that the time spent with each individual customer is at least 3 minutes?
b. If a random sample of 64 customers is selected, what is the probability that the average time spent per customer will be at least 3 minutes?
c. There is an 85% chance that the time spent with an individual customer will be below how many minutes?
d. In a random sample of 64 customers, there is 85% chance that the sample mean will be below how many minutes?