(4) For each of the following scenarios, determine if the random variable is a binomial random variable, a hypergeometric random variable, or neither of these.

a) At a certain furniture store, 10% of its sofa sales are sleeper-sofas. Suppose that the store sells three sofas. Let X be the number of sleeper-sofas sold. Assume that customers make their selections independently.

b) A child's puzzle contains 25 pieces; however, 5 of those pieces have been chewed by the dog. Suppose you reach in and select 10 pieces at random (without replacement). Let X be the number of pieces that you pull out that were chewed by the dog.

c) Suppose that eight customers arrive in a shop and all get in line at the same time. Suppose that the probability that the first customer has to wait more than 5 minutes to be served is 0.05. Let X be the number of customers that have to wait (in line and at the counter) more than 5 minutes to be served.

d) A machine shop has 10 saws. Suppose that there is a 5% chance of any individual saw having a broken blade. Assume that the blades break independently of each other. Let Y be the number of saws that have broken blades at some randomly selected time.