Probability Ques 51
There are four machines and it is known that exactly two of them are faulty. They are tested, one by one, in a random order till both the faulty machines are identified. Then, the probability that only two tests are needed, is
(a) $\frac{1}{3}$
(b) $\frac{1}{6}$
(c) $\frac{1}{2}$
(d) $\frac{1}{4}$
(1998, 2M)
Show Answer
Answer:
Correct Answer: 51.(b)
Solution:
Formula:
- Probability that only two tests are needed =Probability that the first machine tested is faulty $\times$ Probability that the second machine tested is faulty $=\frac{2}{4} \times \frac{1}{3}=\frac{1}{6}$
BETA
