6. 25% of the customers at XYZ Stores use a debit card to pay for their purchases.

In a recent market research study, 18 of the Store's over 20,000 customers on

record was randomly selected for two focus groups on new payment

technologies.

a. Is the selection of 18 customers a binomial experiment? Please explain.

b. What is the probability that 5 of the 18 customers selected use a debit

card to pay for their purchases?

c. What is the probability that at least 4 of the 18 customers selected use a

debit card to pay for their purchases?

d. What is the probability that at most 4 of the 18 customers selected use a

debit card to pay for their purchases?

e. What is the probability that at least 3 but no more than 6 customers

selected use a debit card to pay for their purchases?

7. Customers arrive at the drive-through lane of a fast food restaurant at a rate of

one every 3 minutes. Use the Poisson probability distribution to answer the

following questions:

a. What is the expected number of calls in one hour?

b. What is the probability that exactly two customers arriving at the drive-

through lane in a nine-minutes interval?

c. What is the probability that less than two customers arrive at the drive-

through lane in a nine-minutes interval?

d. What is the probability that two or more customers arrive at the drive-

through lane in a nine-minutes interval?