Simple Interest Practice Test 4

Question : 4 of 26

Marks: +1, -0

A sum of money doubles itself in 7 years at simple interest. In how many years it will become four fold?

Solution:

Let principal be Rs. x; then amount = Rs. 2x, Hence, I = 2x – x = Rs. x.

R = {x×100}/ {x × 100}

= 100/ 7 % \p.\a.

Now, amount = Rs. 4x; then I = 4x – x = Rs. 3x
Hence,

T={3x×100}/{x×100/7}={3×100×7}/100

= 21 years

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