# Simple Interest Questions

Q:

What annual instalment will discharge a debt of Rs 1092 due in 3 years at 12% simple interest?

 A) Rs.325 B) Rs.545 C) Rs.560 D) Rs.550

Explanation:

Let each instalment be Rs.x .

1st year =  [x + (x * 12 * 2)/100]

2nd year = [ x + (x *12 * 1)/100]

3rd year = x

Then, [x + (x * 12 * 2)/100] + [ x + (x *12 * 1)/100] + x =1092

$\inline \Leftrightarrow$3x + ( 24x/100 ) + ( 12x/100 )  = 1092

$\inline \Leftrightarrow$ 336x =109200

$\inline \therefore$ x = 325

Each instalment = Rs. 325

25 9665
Q:

In how many years will a sum of Rs.800 at 10% per annum compounded semi annually become Rs.926.10

 A) 1.5 B) 2.5 C) 3.5 D) 4.5

Explanation:

Let the time be 'n' years, Then

$\inline \fn_cm 800\times (1+\frac{5}{100})^2n=926.10\Leftrightarrow (1+\frac{5}{100})^{2n}=\frac{9261}{8000}\Leftrightarrow \left ( \frac{21}{20} \right )^{2n}=(\frac{21}{10})^3$

$\inline \fn_cm \therefore n=\frac{3}{2} \; or \; n=1\frac{1}{2}$ Years

30 7657
Q:

At what rate percent per annum will a sum of money double in 8 years.

 A) 12.5% B) 13.5% C) 11.5% D) 14.5%

Explanation:

Let principal = P, Then, S.I.=P and Time=8 years

Rate = [(100 x P)/ (P x 8)]% = 12.5% per annum.

12 7368
Q:

A sum of money at simple interest amounts to Rs. 815 in 3 years and to Rs. 854 in 4 years. The sum is:

 A) 650 B) 690 C) 698 D) 700

Explanation:

S.I. for 1 year =  Rs. (854 - 815) = Rs. 39.

S.I. for 3 years = Rs.(39 x 3) = Rs. 117.

Principal = Rs. (815 - 117) = Rs. 698

7 6395
Q:

A certain sum of money amounts to Rs 1008 in 2 years and to Rs 1164 in 3 ½  years. Find the sum and the rate of interest.

 A) 800, 14% B) 800, 13% C) 800, 12% D) 800, 19%

Answer & Explanation Answer: B) 800, 13%

Explanation:

S.I. for 1 ½ years = Rs (1164 - 1008) = Rs 156 .

S.I. for 2 years = Rs (156 x $\inline \frac{2}{3}$ x 2)= Rs 208.

$\inline \therefore$Principal = Rs (1008 - 208) = Rs 800.

Now, P = 800, T= 2 and S.I. = 208.

$\inline \therefore$Rate = (100 x S.I.) / (P x T) = [ (100 x 208)/(800 x 2)]% = 13%