Customers make purchases at a convenience store, on average, every nine minutes. It is fair to assume that the time between customer purchases is exponentially distributed. Jack operates the cash register at this store.

a-1.	What is the rate parameter?(Round your answer to 4 decimal places.)

Rate parameter

a-2.	What is the standard deviation of this distribution?(Round your answer to 1 decimal place.)

Standard deviation

b.	Jack wants to take a seven-minute break. He believes that if he goes right after he has serviced a customer, he will lower the probability of someone showing up during his seven-minute break. Is he right in this belief?
	Yes No

c.	What is the probability that a customer will show up in less than seven minutes?(Round intermediate calculations to 4 decimal places and final answer to 4 decimal places.)

Probability

d.	What is the probability that nobody shows up for over half an hour?(Round intermediate calculations to 4 decimal places and final answer to 4 decimal places.)

Probability