In aptitude (Simple Interest), what principal amount (in ₹) will yield ₹60 as simple interest at 6% per annum in 5 years? (Assume simple interest and use SI = P * r * t / 100.)

Introduction / Context:
This question checks the core simple interest relationship between principal, rate, time, and interest. In simple interest, interest grows linearly with time, and the formula SI = P * r * t / 100 is enough to directly compute the missing value. Here, the interest (₹60), rate (6% per annum), and time (5 years) are known, so we solve for principal P. This is a classic one-formula substitution problem and tests whether you correctly keep the units consistent (percent per annum and years).

Given Data / Assumptions:

• Simple interest, SI = ₹60
• Rate, r = 6% per annum
• Time, t = 5 years
• Formula: SI = P * r * t / 100

Concept / Approach:
Rearrange the simple interest formula to isolate P:
P = (SI * 100) / (r * t) Then substitute the given values and compute the principal.

Step-by-Step Solution:
P = (60 * 100) / (6 * 5) P = 6000 / 30 P = 200

Verification / Alternative check:
If P = ₹200, then SI for 5 years at 6% is 200 * 6 * 5 / 100 = 60, which exactly matches the required interest. This confirms the computed principal is correct.

Why Other Options Are Wrong:
₹175 and ₹150 give SI less than ₹60. ₹250 and ₹300 give SI more than ₹60 because SI increases directly with principal when rate and time are fixed.

Common Pitfalls:
Forgetting to multiply by 100, using 0.06 instead of 6 without adjusting the formula, or mistakenly treating 5 years as 5 months.

Final Answer:
The required principal is ₹200.