Manager salary from averages: The average monthly salary of 20 workers is Rs 1900. When the manager is included, the average becomes Rs 2000 for 21 people. What is the manager's annual salary?

Introduction / Context:
When an additional member changes the average, we recover the person's value by comparing totals before and after inclusion, then annualize by multiplying by 12.

Given Data / Assumptions:

• Workers = 20, average = Rs 1900
• With manager, count = 21, average = Rs 2000

Concept / Approach:
Total = average * count. Monthly manager salary = new total - old total. Annual salary = monthly * 12.

Step-by-Step Solution:

Verification / Alternative check:
Check new average: (38000 + 4000)/21 = 42000/21 = 2000. Correct.

Why Other Options Are Wrong:

• Rs 24000, Rs 25200, Rs 45600: None equal the correct annual total of Rs 48000, hence 'None of these' is correct.

Common Pitfalls:
Forgetting to annualize or mixing monthly and annual figures.

Final Answer: