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JEE MATHEMATICS MCQ: PERMUTATIONS

1 Easy

1 of 1

Application +4 | -1

If

{ }^{{n}} P_{{r}}=2520

and

{ }^{{n}} C_{{r}}=21

then

n

is equal to:

View answer and explanation

Correct option: B

7

Option B (7) is correct because by using the given values of

{}^{{n}} P_{{r}}

and

{}^{{n}} C_{{r}}

, we can find r=5 and then solve for n, which results in n=7.

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