Here’s and example of a **SMART MATH** problem for **PERCENTAGES.**

**Problem**

**Problem**

A money lender lends $400 for 2 years and $200 for 3 years, at the same rate on simple interest and receives $70 as interest. What is the interest rate?

- 3.33%
- 4.00%
- 5.00%
- 8.33%
- 12.5%

**The Usual Method**

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Let ‘*r*’ be the rate of interest.

Hence, interest earned on $400 for 2 years =

Similarly, interest earned on $200 for 3 years =

Hence, total interest earned = = $70

%

**(Ans: 3)**

*Estimated Time to arrive at the answer = 45 seconds.*

**Using Technique**

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Interest on $400 for 2 years is equivalent to that for $200 for 4 years. Thus effectively $200 can be said to be lent for 4 + 3 = 7 years

Interest earned =

%

**(Ans: 3)**

*Estimated Time to arrive at the answer = 15 seconds.*

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