Question

Please only answer if you are confident that the answer is actually correct, I asked this question before but got the wrong answer thank you.

University Level Answer.

Question 6: A shipment of 10 cameras includes 3 that are defectives. a. 4 cameras from the shipment were randomly selected without replacement and tested. Let X be the number of defectives selected. Find P(X-2). b. Let Y be the number of cameras from the shipment were randomly selected without replacement and tested until all the detectives were found. Find P(Y = y).

Answer 1

(a)

Here x can take values 0, 1, 2, 3. Number of ways of selecting 4 cameras out of 10 is

101 210 (10.4) = 4!(10-4)!

Number of ways of selecting x defective out of 3 and 4-x non defective out of 10-3=7 non defectives is

So

(b)

Here y can take values 3,4,...10. When Y=3 then all defective are tested at first three selection so

When Y=4 then two defectives are in first three and one at 4th selections so

3.2.1 C(3,2) 10.9.8 10 9 8 7

Likewise

Continuing in this manner