If ${ }^{{n}} C_r:{ }^{{n}} C_{r+1}:{ }^n C_{r+2}=1: 2: 3$, then $r$ is equal to

JEE MATHEMATICS MCQ: COMBINATIONS

1 Easy

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Application +4 | -1

{ }^{{n}} C_r:{ }^{{n}} C_{r+1}:{ }^n C_{r+2}=1: 2: 3

, then

r

is equal to

View answer and explanation

Correct option: B

Option A (7/11(12!)) is correct because it is the result of multiplying the number of ways to choose the consonants and vowels by the number of ways to arrange them.

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, then

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