Question

A ot· se spac g wash (e-g. 98.7654). s cortan s 10 wash en that are thicker than the target dr ension suppose that three washers are selected at random, without replace et tomthe lot. Round your answers to four aci ai plec (b) What is the probability that the third washer selected is thicker than the target if the first two selected are, thinner than the target?

Answer 1

(a) This is the probability of choosing 3 washers from 10 thick washers out of choosing 3 washers from total 50 washers. So, the probability is:

$P= \frac{ ^{10}C_3}{^{50}C_3}=0.0061$

(b)  This is the probability of choosing 2 washers from 40 thin washers and 1 washer from 10 thick washers out of choosing all 3 from total 50 washers.

$P= \frac{ ^{40}C_2\times \:^{10}C_1 }{^{50}C_3}=0.3980$

(c)  The probability of choosing 1 washer from 10 washers and 2 washers from remaining 49 washers.

$P= \frac{ ^{49}C_2\times \:^{10}C_1 }{^{50}C_3}=0.6$