﻿ 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 : Kaysons Education

# 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

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## Question

### Solution

Correct option is

1/6

The probability that only two tests are needed = (probability that the first machine tested is faulty) × (probability that the second machine tested is faulty given that the first machine tested is faulty).

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