Customers arrive at Flourish and Blotts randomly and independently of each other at a rate of 10 per day, on average.

Customers arrive at Flourish and Blotts randomly and independently of each other at a rate of 10 per day, on average. Assume that Flourish and Blotts is open 24 hours a day and a customer has just arrived.

a) What is the average time between customers and the standard deviation of the time between customers?

b) What is the probability that the next customer arrives in the next hour?

c) What is the probability that no customers arrive in the next hour?

d) What is the probability that the next customer arrives in 60 - 90 minutes time?