Find the simple interest on ₹600 for 11 months if the rate of interest is 5 paise per rupee per month (that is, 5% per month) under simple interest.

Introduction:
This question tests converting a non-standard rate statement (“paise per rupee per month”) into a percentage and applying simple interest for a time given in months. The phrase 5 paise per rupee per month means interest is 5 paise for every 1 rupee each month, which equals 5% per month. Then we apply SI = (P * r * t) / 100 using monthly time units consistently.

Given Data / Assumptions:

• Principal P = ₹600
• Time t = 11 months
• Rate r = 5% per month (since 5 paise per rupee = 5/100 = 5%)
• Simple interest formula: SI = (P * r * t) / 100

Concept / Approach:
Because the rate is explicitly “per month,” we can keep time in months (no need to convert to years). Substitute P = 600, r = 5, t = 11 into the simple interest formula and compute.

Step-by-Step Solution:
SI = (P * r * t) / 100 SI = (600 * 5 * 11) / 100 SI = (600 * 55) / 100 SI = 33000 / 100 SI = 330

Verification / Alternative check:
5% of ₹600 per month is ₹30 per month. Over 11 months, interest = 30 * 11 = ₹330, matching the formula result.

Why Other Options Are Wrong:
₹30 is only one month’s interest. ₹33 and ₹3.30 come from decimal mistakes. ₹300 is close but does not match 11 months exactly. Only ₹330 fits correctly.

Common Pitfalls:
Converting to annual rate unnecessarily (which can still work if done correctly), confusing paise with rupees, or forgetting to multiply by 11 months.

Final Answer:
The simple interest is ₹330.