SOLUTION: Andrew recently opened a barbershop and is trying to figure out how much shaving cream he should buy on a regular basis. He has found that for the first two months the probability

Question 1118180: Andrew recently opened a barbershop and is trying to figure out how much shaving cream he should buy on a regular basis. He has found that for the first two months the probability that a customer needs a haircut is 0.6, the probability that a customer needs a shave is 0.4, and the probability that a customer needs a haircut or a shave is 0.9. What is the probability a customer will need both a haircut and a shave?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
P(A or B)=P(A)+P(B)-P(A and B), where A is haircut and B is a shave.
0.9=0.6+0.4-P(A and B)
P(A and B)=0.1
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