As a quality control manager, you are responsible for checking the quality level of AC adapters for tablet PCs that your company manufactures. You must reject a shipment if you find 4 defective units. Suppose a shipment of 40 AC adapters has 8 defective units and 32 non defective units. If you sample 12 AC adapters, what's the probability that
a. There will be no defective units in the shipment?
b. There will be at least 1 defective unit in the shipment?
c. There will be 4 defective units in the shipment?
d. The shipment will be accepted?