JEE Main 2020MathematicsPermutation CombinationHardNumerical

JEE Main 2020Permutation Combination Question with Solution

JEE Main 2020 (04 Sep Shift 2)

Question

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 ___________

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Show full solutionCorrect answer: 135
Correct answer
135

Step-by-step explanation

No. of ways of giving wrong answer =3

So, required no. of ways =C46(1)4×(3)2
=15(9)=135

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About this question

This is a previous-year question from JEE Main 2020, covering the Permutation Combination chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.