Question

A sum of money doubles itself in 8 years. what is
1 .the rate of interest?
2. In how many years will the sum become triple of itself at the same rate percent ?

Answer 1

Answer:

Part 1:     Rate of Interest is 12.5 %.

Part 2:     Amount is tripled in 16 years.

Step-by-step explanation:

Let the Principal Amount, P = Rs. x

Part 1).

Given: Time period to get double , T = 8 years

            Amount, A = Rs. 2x

To find: Rate of interest.

We know that ,

Simple Interest, SI = A - P = 2x - x = x

Now, Using Simple Interest formula,

$SI=\frac{P\times R\times T}{100}$

$x=\frac{x\times R\times8}{100}$

R = 100/8 = 12.5 %

Therefore, Rate of Interest is 12.5 %

Part 2).

Given: Amount , A = Rs. 3x

           From Part 1.  Rate , R = 12.5 %

           Again, SI = 3x - x = 2x

To find: Time in which amount is tripled.

Using Simple Interest Formula, we get

$SI=\frac{P\times R\times T}{100}$

$2x=\frac{x\times12.5\timesT}{100}$

T = 2 × 8

T = 16

Therefore, Amount is tripled in 16 years.