The amount of time a bank teller spends with each customer has a population mean μ = 3.10 minutes and standard deviation σ = 0.40 minutes. If a random sample of 16 customers is selected,
(a) What is the probability that the average time spent per customer will be at least 3 minutes?
(b) There is an 85% chance that the sample mean will be below how many minutes?
(c) What assumption must be made in order to solve (a) and (b).
(d) If a random sample of 64 customers is selected, there is an 85% chance that the sample mean will be below how many minutes?
(e) What assumptions if any, must be made in order to solve (d)?
(f) Which is more likely to occur - an individual service time below two minutes, a sample mean above 3.4 minutes in a sample of 16 customers, or a sample mean below 2.9 minutes in a sample of 64 customers? Explain.