Question:
The number of all three elements subsets of the set $\{a_1, a_2, a_3 . . . a_n\}$ which contain $a_3$ is
The number of all three elements subsets of the set $\{a_1, a_2, a_3 . . . a_n\}$ which contain $a_3$ is
Updated On: Dec 19, 2025
- $^nC_3$
- $^{n - 1} C_3$
- $^{n - 1} C_2$
- None of these
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The Correct Option is C
Solution and Explanation
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 $^{n -1}C_2$.
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