Question

In what time does a sum of money becomes four times at the
simple interest rate of 10% per annum ?
(A) 30 years (B) 25 years (C) 35 years (D) 40 years​

Answer 1

Answer:

Time taken in years = 30 years

Option (A)

Step-by-step explanation:

Let principal be x

A = 4x

Rate of interest = 10%

SI = A - P

SI = 4x - x

SI = 3x

T =100×SI/P×R

T = 100×3x/x×10

T= 30

Answer 2

Answer:

Option (A) 30 years

Step-by-step explanation:

Let Principal money, P be Rs 1.

Rate of interest,r = 10%

Time period be t years.

So, Amount, A = 4 times principal sum of money = 4*1 = Rs 4.

Now, Amount = Principal + Simple Interest

                   A  = P + (P * r * t)

                   A = P(1 + (r * t))

                   4 = 1(1 + (0.10 * t))

               4 - 1 = 0.1*t

                 3 = 0.1*t

                 t = 3/0.1 = 30

Therefore, Time period, t = 30 years.

So, In 30 years a sum of money becomes four times at the  simple interest rate of 10% p.a.