CMAT 2013 Solved Question Paper

Question : 1 of 100

Marks: +1, -0

There are four calculators and it Is known that exactly two of them are defective. They are tested one-by-one, in a random order till both the defective calculators are identified. Then, the probability that only two test are required is

Validate

Solution:

^4C_2

= 6. If only two tests are required to identify defective calculators, then in first two tests defective calculators are identified.
This can be down in one way only
∴ Required probability = 1/6

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