Question

There are four machines and it is known that eactly two of them are faulty. They are tested, one by one, in a random order till both the faulty machines are identified. The probability that only two tests are needed is (A) `1/6` (B) `1/3` (C) `1/2` (D) `1/4` A. `(1)/(3)` B. `(1)/(6)` C. `(1)/(2)` D. `(1)/(4)` Select the correct answer from above options

Answer 1

Correct Answer - B Probability that only two tests are needed =Probability that the first machine tested is faulty `xx` Probability that the second machine tested is faulty `=(2)/(4)xx(1)/(3)=(1)/(6)`