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JEE MATHEMATICS MCQ: PERMUTATIONS

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The number of ways in which the digits

1,2,3,4,3

, 2,1 can be arranged so that the odd digits always occupy the odd places, is

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Correct option: C

18

Option C (18) is correct because the odd digits (1, 3, 3, 1) can be arranged in odd places in

\frac{{4!}}{{2!2!}}

ways, and the even digits (2, 4, 2) can be arranged in even places in

\frac{{3!}}{{2!}}

ways, so the total number of ways is

\frac{{4!}}{{2!2!}} \times \frac{{3!}}{{2!}} = 18

.

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