The number of all three elements subsets of the set { a 1 , a 2 , a 3 … a n } which contain a 3 is

Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationnPr & nCrEasy2 minPYQ_2014

MathematicsEasysingle choice

The number of all three elements subsets of the set ${a_{1}, a_{2}, a_{3} \dots a_{n}}$ which contain $a_{3}$ is

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Answer:

Solution:

The number of three elements subsets containing $a_{3}$ is equal to the number of ways of selecting 2 elements out of $n - 1$ elements. So, the required number of subsets is $^{n - 1} C_{2}$

Stream:BITSATSubject:MathematicsTopic:Permutation & CombinationSubtopic:nPr & nCr

⏱ 2mℹ️ Source: PYQ_2014

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