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Mediumcombinations

~75s

Selecting from two groups

A committee of 5 is to be chosen from 6 men and 4 women so that it contains exactly 3 women. In how many ways?

Show the answer and the worked solution

Correct answer: B.

60

Worked solution

  1. Women: C(4,3) = 4.
  2. Men: C(6,2) = 15.
  3. Total = 4 × 15 = 60.

Answer: 60.

The idea

Independent selections from separate groups multiply. Check the numbers add to the committee size: 3 + 2 = 5. ✓

Shortcut. Exactly 3 women forces exactly 2 men: C(4,3) = C(4,1) = 4 and C(6,2) = 15, so 4 × 15 = 60.

Common trap. "120" — choosing the 2 men as 6 × 5 = 30 without halving for order, then 4 × 30 = 120.

Permutations & Combinations

30 of 35

Level

Medium

Target time

~75s

Selecting from two groups — Aptitude Question

Selecting from two groups: A committee of 5 is to be chosen from 6 men and 4 women so that it contains exactly 3… Answer and worked solution on CodeKairo.

Question

A committee of 5 is to be chosen from 6 men and 4 women so that it contains exactly 3 women. In how many ways?

Options

  1. 40
  2. 60
  3. 84
  4. 120
Show the answer and the worked solution

Correct answer: B. 60

Worked solution

  1. Women: C(4,3) = 4.
  2. Men: C(6,2) = 15.
  3. Total = 4 × 15 = 60.

Answer: 60.

The idea

Independent selections from separate groups multiply. Check the numbers add to the committee size: 3 + 2 = 5. ✓

Shortcut. Exactly 3 women forces exactly 2 men: C(4,3) = C(4,1) = 4 and C(6,2) = 15, so 4 × 15 = 60.

Common trap. "120" — choosing the 2 men as 6 × 5 = 30 without halving for order, then 4 × 30 = 120.

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