Question

. On a certain sum of money, invested at the rate of 5% per annum C.I annually, the difference between the interest of the first year and the interest of the third year is 61.50. Find the sum.​

Answer 1

Answer:

Let the sum (Principle) = Rs. 100

C.I. of 1st year = Rs. \frac{100\times 5\times 1}{100} = Rs. 5$$

And, amount of 1st year = Rs. 100 + Rs. 5=Rs. 105$$

⇒ The principke for 2nd year = Rs. 105

C.I. of 2nd year =Rs.

100

105×5×1

=Rs.5.25

And, amount of 2nd year =Rs.105+Rs.5.25=Rs.110.25

⇒ The principle for 3rd year =Rs.110.25

C.I. of 3rd year =Rs.

100

110×5×1

=Rs.5.5125

Difference between C.L of 1st year and C.L of 3rd year =Rs.5.5125−Rs.5=Rs.0.5125

Now, when the difference of interest =Rs.0.5125,sum=Rs.100

And, when the difference of interest =Rs.61.50,sum=Rs.

0.5125

100

×61.50=Rs.12,000