A salary increases from ₹ 7200 to ₹ 8100. By what percentage has the salary increased?

Introduction / Context:
Percentage change problems require computing the change relative to the original value. Here, the original salary and the new salary are given directly.

Given Data / Assumptions:

• Original salary = ₹ 7200.
• New salary = ₹ 8100.

Concept / Approach:
Percentage increase = (Increase / Original) * 100. Increase equals New − Original. Always divide by the original amount when computing the rate of increase.

Step-by-Step Solution:
Increase = 8100 − 7200 = 900Rate = (900 / 7200) * 100 = 0.125 * 100 = 12.5%12.5% = 12 1/2%

Verification / Alternative check:
Compute 12.5% of 7200: 0.125 * 7200 = 900. Add to 7200 to get 8100, confirming the result.

Why Other Options Are Wrong:
25%, 18%, 16 2/3%, and 15% correspond to different increases; none produce exactly ₹ 8100 from ₹ 7200.

Common Pitfalls:
Dividing by the new amount instead of the original, which would understate the true percentage change.

Final Answer:
12 1/2%