NDA 2025 · PYQ · Permutations and Combinations · easy
What is the number of selections of at most 3 things from 6 different things?
A.20
B.22
C.41
D.42✓ Correct
Explanation
At most 3 means 1 + 2 + 3 things (or possibly including 0). C(6,1) + C(6,2) + C(6,3) = 6 + 15 + 20 = 41. Including 0 things (empty selection): 41 + 1 = 42. The answer 42 includes empty selection.
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