Aditi invests ₹10,000, part of it at 6% and the rest at 8% per annum simple interest. Her total interest for one year is ₹720. How much did she invest at 6%?

₹4,000Correct answerYour answer₹5,000Correct answerYour answer₹6,000Correct answerYour answer₹9,000Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

If all ₹10,000 were at 8%, the interest would be ₹800.
The actual interest is ₹720, which is ₹80 less.
Each ₹100 moved to 6% loses ₹2, so the amount at $6\% = (80 \div 2) \times 100$ = ₹4,000.

Worth noting

₹6,000 is the part invested at 8%, and ₹9,000 treats all the interest as earned at 8%. Check: $6\% \text{ of } 4{,}000 + 8\% \text{ of } 6{,}000 = 240 + 480$ = ₹720.

Concept: Splitting a sum between two simple-interest rates
Typical timeTypical: 70 s
Your timeYours: —

The rule this testsSimple interest

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Ten questions from Simple & Compound Interest, at your own pace.

Aditi invests ₹10,000, part of it at 6% and the rest at 8% per annum simple interest. Her total interest for one year is ₹720. How much did she invest at 6%?

Explanation