Probability

Question

A Computer company manufacture computer chips used in DVD players. Those chips area made with 47% yield meaning that 47% of them are good and the others are defective.

a) If one chip is randomly selected, find the probability that it is not good ( I think 1-.47=.53 or 53%)

b) If two chips are randomly selected, find the probability that they are both good (I think .47 X .47 = .2209)

c) If three chips are randomly selected, find the probability that at least one is good…this is where I am stuck

Answer 1

 

Hi Joe,

 

As to the problem c),

we can think of the probability that none out of three is good,

which is given by

 

     Prob(None out of 3 is good) = 0.53 · 0.53 · 0.53

 

                                              = 0.1489

 

The case where at least one is good is actually

the opposite to the case where none out of three is good,

i.e., the two cases are exclusive to each other.

 

So, the answer to c) is

 

     Prob(At least one is good) = 1 - 0.1489

 

                                            = 0.8511