Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationnPr & nCrHard2 minPYQ_2020

MathematicsHardnumerical

A test consists of $6$ multiple choice questions, each having $4$ alternative answers of which only one is correct. The number of ways, in which a candidate answers all six questions such that exactly four of the answers are correct, is ___________

Answer:

135.00

Solution:

No. of ways of giving wrong answer $= 3$

So, required no. of ways $= {}^{6}C_{4} (1)^{4} \times (3)^{2}$
$= 15 (9) = 135$

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:nPr & nCr

⏱ 2mℹ️ Source: PYQ_2020

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