A retail computer store sells IBM personal computers (PCs) and compatibles. Assume that 80% of the PCs that the store sells are IBM PCs and 20% are compatibles.
a. Find the probability that all of the next four PC purchases are compatibles.
Hint:
i. Define the experiment.
ii. List the simple events.
iii. Assign probabilities to the simple events.
iv. Determine the collection of simple events contained in the event of interest.
v. Sum the simple event probabilities to obtain the event probability.


第二第三问就好