Question

A quality control inspector has determined that 0.25% of all parts manufactured by a particular machine are defective. If 50 parts are randomly selected, find the probability that there will be at most one defective part.

Answer 1

9.941*10^-6

Explanation:

Probability of at most 1 means not more than 1 defective= probability of 1 or probability of 0

Probability of 1 = 50C1(0.25)(0.75)^49

Probability= 50(0.25)*7.55*10^-7

Probability= 9.375*10^-6

Probability of 0

= 50C0(0.25)^0(0.75)^50

= 1(1)(0.566*10^-6)

= 0.566*10^-6

Total probability

= 9.375*10^-6+ 0.566*10^-6

= 9.941*10^-6