A shipment of 20 integrated circuits (ICs) arrives at an electronics manufacturing site. The site manager will randomly select 4 ICs and test them to see whether they are faulty. Unknown to the site manager, 5 of these 20 ICs are faulty.
a. Suppose the shipment will be accepted if and only if none of the inspected ICs is faulty. What is the probability this shipment of 20 ICs will be accepted?

b. Now suppose the shipment will be accepted if and only if at most one of the inspected ICs is faulty. What is the probability this shipment of 20 ICs will be accepted?

c. How do your answers to (a) and (b) change if the number of faculty ICs in the shipment is 3 instead of 5? Recalculate (a) and (b) to verify your claim.