Question 1
A committee of 5 members is to be formed from 6 men and 4 women. In how many ways can this be done if the committee must have exactly 3 men and 2 women?
Step-by-Step Solution:
Concept: Combination with constraints - selection from multiple groups with specific requirements.
Given:
- Men available: 6
- Women available: 4
- Committee size: 5
- Required: 3 men and 2 women
Strategy: Select from each group independently, then multiply (Multiplication Principle).
Step 1 - Select Men:
Choose 3 men from 6 men = C(6,3)
C(6,3) = 6! / [3! × 3!] = 20
Step 2 - Select Women:
Choose 2 women from 4 women = C(4,2)
C(4,2) = 4! / [2! × 2!] = 6
Step 3 - Apply Multiplication Principle:
Total ways = C(6,3) × C(4,2)
= 20 × 6
= 120
Key Principle: When selecting from different independent groups with specific requirements from each:
- Calculate selections from each group separately
- Multiply the results
Common Error: Don't add the combinations - multiply them! Each selection from one group can be paired with each selection from the other.
Concept: Combination with constraints - selection from multiple groups with specific requirements.
Given:
- Men available: 6
- Women available: 4
- Committee size: 5
- Required: 3 men and 2 women
Strategy: Select from each group independently, then multiply (Multiplication Principle).
Step 1 - Select Men:
Choose 3 men from 6 men = C(6,3)
C(6,3) = 6! / [3! × 3!] = 20
Step 2 - Select Women:
Choose 2 women from 4 women = C(4,2)
C(4,2) = 4! / [2! × 2!] = 6
Step 3 - Apply Multiplication Principle:
Total ways = C(6,3) × C(4,2)
= 20 × 6
= 120
Key Principle: When selecting from different independent groups with specific requirements from each:
- Calculate selections from each group separately
- Multiply the results
Common Error: Don't add the combinations - multiply them! Each selection from one group can be paired with each selection from the other.