Two part question please answer both parts and show all work

Two part question, please answer both parts and show all work to justify final answer. Thank you.

Your store has, on average, 40 customers per hour.

What is the probability your next customer will enter in the next minute?

What is the probability you will not get a customer in the next five minutes?

Solution

40 customers in 60 mins

therefore 20 customers in 30 mins , 10 customers in 15 mins

therefore it takes 1.5 minute for next customer to come.

probability that customer will come in next minute is 1/2*1/2 = 1/4 (as from above on average 1.5 mins it takes to come and probability will be 1/2*1/2)

probability of not getting the customer in 5 minutes will be (1/2)^5 = 1/32