Question

A sum of money at simple interest amounts to rs. 9,440 in 3 years. if the rate of interest is increased by 25%, the same sum of money amounts to rs. 9,800 in the same time. find the rate of interest.

Answer 1

Let Principle be P and rate is R
Equation 1 = P + (P x 3 x R/100) = 9440
Equation 2 = P + (P x 3 x (R x 1.25)/100) = 9800
by solving these equation we get 
P = 8000
R = 6

Answer 2

Answer :

Principle = Rs. 8000

Rate = 6%

After 25% increase in rate, Rate became 7.5 %

Step by Step Explanation :

Hey Mate,

Given Data :

The Sum of Amount at S.I after 3 Year is Rs 9,440.

The Sum of Amount at S.I after 3 Year is Rs 9,800, If rate of interest is increase by 25%.

Solution :

We will solve this question with easy trick. Lets take the  round figure of 9440.

Suppose, P = 9000 ; So, S.I = 440

S.I = PRT/ 100

440 =  ( 9000 × R × 3 ) / 100

440/ (270) = R

R = 1.6296........

Rate came out in Irrational number. So, lets take P = 8000

S.I = PRT/ 100

1440 =  ( 8000 × R × 3 ) / 100

1440/ (240) = R

R = 6%

So,

Principle = 8000 and the Rate = 6%

After 25% increase in rate, Rate became 7.5 %