Question

At what rate of annual simple interest will Rs. 10000 double in 15 years?

Answer 1

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Here is your answer,⬇⬇⬇⬇

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The answer is 6.67% per annum

While calculating simple interest we look for 4 parameters:

Principal(P): which is 10000 in this case

Rate(R): which is to be calculated

Time(T): which is 15 years in the problem

Amount(A): since the principal doubles itself in 15 years, the amount will be 20000

Applying the formula for amount,

A= P+ (P*R*T)/100

We get,

20000= 10000+ (10000*R*15)/100

On solving the above equation for R, we get

R= 6.67% per annum.

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Hope it helps you!✔✔✔✔

Answer 2

We know that

Amount=$P+\frac{PRT}{100}$  

So, here P = 10000  

R = ?  

T = 15 years  

A = 20000  [∵ Principal doubles in 15 years]

So, we get  

20000=10000+$\frac{10000*R*15}{100}$  

20000-10000=1500×R  

10000 = 1500R  

R=$\frac{10000}{1500}$  

∴ R = 6.67% per annum