CAT Quantitative Ability Questions | CAT Permutation, Combination and Probability questions

CAT/2001

Question . 45

Let n be the number of different 5 digit numbers, divisible by 4 with the digits 1, 2, 3, 4, 5, and 6, no digit being repeated in thenumbers. What is the value of n?

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Explanatory Answer

Method of solving this CAT Quantitative Ability Question from Permutation, Combination and Probability question

(c) For a number to be divisible by 4, its last two digitsshould be divisible by 4.

i.e., the last two digits should be 12, 16, 24, 32, 36, 52, 56or 64.

No. of numbers end with 12 = 4C3 × 3! = 24

Similarly number of numbers end with 16, 24, 32, 36, 52,56 or 64 each = 24.

Thus, value of n = 24 × 8 = 192