SOLUTION: Please help me solve the probability question. The record of a department store show that 10% of their customers who make a purchase return the merchandise in order to exchange

Question 1076606: Please help me solve the probability question.
The record of a department store show that 10% of their customers who make a purchase return the merchandise in order to exchange it. What is the probability that in the next eight purchases three customers return the merchandise for exchange.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
binomial
8C3(.1)^3*.9^5
There are 8C3=56 ways three may be chosen, and the probabilities add to 1 and the exponents to 8
0.0330
This is low, does it make sense?
The expected value is about 1 (0.8 to be exact), and the sd is about 0.85, so this is a reasonable answer.
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