SOLUTION: A retailer purchases 210 of a new brand of DVD player, of which 4 are defective. The purchase agreement says that if he tests 5 chosen at random and finds 1 or more defective, he r

Algebra ->  Probability-and-statistics -> SOLUTION: A retailer purchases 210 of a new brand of DVD player, of which 4 are defective. The purchase agreement says that if he tests 5 chosen at random and finds 1 or more defective, he r      Log On


   

Question 1150040: A retailer purchases 210 of a new brand of DVD player, of which 4 are defective. The purchase agreement says that if he tests 5 chosen at random and finds 1 or more defective, he receives all the DVD players free of charge. What is the probability that he will not have to pay for the DVD players?
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
number of ways to choose 5 is 210C5
find probability all are not defective is the complement of the answer.
that is 206C5
Also, the probability of the first not being defective is 206/210, the second 205/209. then 204/208, and 203/207.
That probability is 0.9075 of not being defective.
The question asks for probability of at least 1 being defective (so he doesn't have to pay), and that is the complement or 0.0925.