Question

a sum of a sum of money at simple interest amounts to 915rupees in 3 years and to 945 rupees in 4 year calculate the sun

Answer 1

825 rs is the answer.. please refer to the attachment

Answer 2

Let profit = p
Amount = 915 and 945
Rate = r
Time = 3 years and 4 years
Si for 3 years = p×r×3/100
=> 3pr/100
Si for 4 years = p×r×4/100
=> pr/25

Now,
Pr for 3 years
=> 3pr/100 = 915
=> pr = 915×100/3
=> pr = 3500

Now Si for 3 years = p×r×t /100
=> 3500×3/100
=> 105
Principle = amount - si
=> 915 - 105
=> 810

Rate = si×100/p×t
=> 105×100/810×3
=> 350/81
=> 4.32%

Principle = si×100/r×t
=> 105×100/4.32×3
=> 810

Rate = 4.32%
Principle = 180 rupees