Question

In what time will a sum of money put at 15% simple interest triple itself?

Answer 1

Let P = a, Then A will be 3a.

We know that I = A - P

                          = 3a - a = 2a

 SI = PRT/100

 2a = a * 15 * t/100

t = (2a*100)/(a*15)

  = 40/3

  = 13.3 years. 

Answer 2

Given:

Rate of interest,

R = 15%

Let Principle (P) = a

then according to the question, the amount (A) will be = 3a

To find:

Time = ?

Solution:

As we know,

⇒  $I=A-P$

On putting the values, we get

⇒     $=3a-a$

⇒     $=2a$

Now,

⇒  $SI=\frac{P\times R\times T}{100}$

On substituting the given values in the above formula, we get

⇒  $2a=\frac{a\times 15\times T}{100}$

⇒ $200=15T$

⇒   $T=\frac{200}{15}$

⇒   $T=13.3 \ years$

Thus the time is "13.3 years".