Question

The simple interest on a certain sum for 4 years at 9% per annum is 114 more than the simple interest on the sum for3 years at 10% per annum find the sum

Answer 1

Here there are two same amounts invested for different tenures.

First one is invested for 4 years at 9% and interest received = x (say)

for second one, interest received = 114 less = x-114

x-114 = P(3)(0.10) and x = P(4)(0.09)

Now we have to solve for P

Subtract first from second to get

114 = P(0.36)-P(0.30)  = 0.06P

P = 114/0.06 = 1900

Hence the sum = 1900 rupees