A shipment of 60 inexpensive digital watches, including 9 that are defective,is sent to a department store.The receiving department select's 10 at random for testing and rejects the whole shipment if 1 or more in the sample are found defective.What is the probability that the shipment will be rejected?

Respuesta :

Answer:  0.627 or 62.7 %

Step-by-step explanation:

The probability that shipment will be rejected P(rejected) = 1- probability that shipment will be accepted.

P(rejected)= 1-P(accepted)

P(accepted) is equal to probability when all 10 watches are not defective.

The probability that 1st one randomly selected watches are not defective is 51/60  (51 watches are not defective and 9 are defective)

The probability that 2-nd one randomly selected watches are not defective is  50/59 ( because the total number of the watches now is 1 unit less 60-1=59, and the total number of not defective watches is 1 unit less 51-1=50 units)

The probability that 3rd one randomly selected watches are not defective is 49/58  (49 watches are not defective total number of watches is 58)

Similarly P(4th)= 48/57  P(5th)=47/56   P(6th)=46/55  P(7th)=45/54

P(8th)=44/53  P(9th)=43/52  P(10th)=42/51

So P(accepted)= P(1st)*P(2nd)*P(3rd)*P(4th)*P(5th)*P(6th)*P(7th)*P(8th)*P(9th)*P(10th)=

=51*50*49*48*47*46*45*44*43*42/(60*59*58*57*56*55*54*53*52*51)=

= approx= 0.373

So P(rejected)=1-0.373=0.627