Probability

2010-11-25 3:28 am

can anyone help me?

A warehouse has ten second-hand laser printers for sale .Four of them are defective .A company select five of the printers at random, thinking that all in good working condition .If <x>is the random variable representing the number of defective printer that the company has choose ,

<1>what is the probability that the company would get two defective printers among the five choosen ?

<2>what is the probability that the company would get fewer than two defective printer among the five chosen?

回答 (1)

Acct

2010-11-25 6:52 am

✔ 最佳答案

Probability of defective printer = 4 /10 = 0.4
Probability of not defective printer = 6 /10 = 0.6<1>what is the probability that the company would get two defective printers among the five choosen ?nCr=(2C5)=10Ans: 0.4 x 0.4 x 0.6 x 0.6 x 0.6 x 10
= 0.3456<2>what is the probability that the company would get fewer than two defective printer among the five chosen? nCr=(1C5)=5Ans: 0.4 x 0.6 x 0.6 x 0.6 x 0.6 x 5
= 0.2592

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