Question

A company manufactures marbles. Over a year, it is observed that 70% of the marbles manufactured pass the quality check and 30% are rejected. 60% of the rejected marbles undergo reprocessing, while the rest go into scrap. What is the probability that out of 15 marbles selected at random exactly 3 marbles go into scrap?

A) 0.17
B) 0.12
C) 0.22
D) 0.29

Answer 1

Answer:0.17

Explanation:

Answer 2

Out of the 30% rejected, (30%)(60%) = 0.18 undergo reprocessing, while (30%)(1 - 60%) = 0.12 go into scrap. Therefore the probability that 1 marble is scrapped is 0.12. Using the binomial theorem for 3 out of 15:
P = (15C3)(0.12)^3 (1 - 0.12)^12 = 0.1696 ~ 0.17, which is choice A.