Question

How many ways can a committee of four students be selected from a 15-member club? a.15!44! b.15!11!×4! c.15×14×13 d.B and C

Answer 1

• B) 15! / (11! × 4!)

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This is a combination of 4 out of 15.

Use combination formula:

• nCr = n! / ((n - r)! × r!),

where C - number of combinations, n- total number of objects, r - number of choosing from objects

Substitute 15 for n and 4 for r to get:

• 15C4 = 15! / ((15 - 4)! × 4!) = 15! / (11! × 4!)

Correct choice is B.