SOLUTION: A computer retail store has 8 personal computers in stock. A buyer wants to purchase 4 of them. Unknown to either the retail store or the buyer, 4 of the computers in stock have de
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Question 1176464: A computer retail store has 8 personal computers in stock. A buyer wants to purchase 4 of them. Unknown to either the retail store or the buyer, 4 of the computers in stock have defective hard drives. Assume that the computers are selected at random.
a) In how many different ways can the 4 computers be chosen?
Answer: 8C4=70
b) What is the probability that exactly one of the computers will be defective?
Answer: (4)(4)=16 , 16/70
c)What is the probability that at least one of the computers selected is defective? Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website! a. is correct
b is (4C1)(4C3/8C4=16/70 correct
c. what is the probability NONE is defective, which is (4/8)(3/7)(2/6)(1/5)=24/1680=(1/70)
that is also (4C0)*(4C4)/8C4=1/70
at least one is defective is the complement of 1/70 or 69/70.
