Difficulty: Medium
Correct Answer: 6
Explanation:
Introduction / Context:
Mixture (weighted average) problems with two groups can be solved by equating total ages computed from averages. Once the number of women is known, subtract married to get unmarried.
Given Data / Assumptions:
Concept / Approach:
Total age = average * count. If w is women count, set 16*8 + 22*w = 15*(16 + w) and solve for w. Then unmarried = w - married.
Step-by-Step Solution:
Verification / Alternative check:
Totals: 128 + 22*16 = 128 + 352 = 480; group size = 32; 480/32 = 15, consistent.
Why Other Options Are Wrong:
Common Pitfalls:
Forgetting to multiply averages by group sizes or mixing up the subtraction of married from total women.
Final Answer:
Discussion & Comments