Question

Difficulty: Very hardCombinations and Group Selections

A committee of 55 members is to be formed from a pool of 66 men and 55 women. The committee must include at least 22 men and at least 22 women. However, two specific individuals in the pool, one man and one woman, refuse to serve on the committee together. How many different valid 55-member committees can be formed?

Answer: 280

Answer

The correct answer is 280.
The correct answer is 280, found by taking the total possible committees satisfying the gender constraint (350) and subtracting the invalid committees containing both conflicting members (70).

Step-by-Step Solution

1
Calculate total combinations satisfying gender constraints without individual restriction
350 valid gender-balanced committees (200 from 3M/2W and 150 from 2M/3W)
Establishes the total baseline number of committee selections before removing forbidden pairings
2
Calculate forbidden combinations containing both specific conflicting individuals
70 forbidden combinations (40 with 3M/2W overall and 30 with 2M/3W overall)
Identifies committee selections that violate the condition that the two individuals cannot serve together
3
Subtract forbidden combinations from total baseline combinations
280 valid committee selections
Applying complementary counting (35070350 - 70) yields the exact number of allowable committees

Key Concept

Combinations with group constraints and complementary counting
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