Question

A sum of ₹ 1000 is invested at 8 % simple interest per year. Calculate the interest at the end of each year. Do these interests from an AP? If, so find the interest at the end of 30 years making use of this fact. ​

Answer 1

We know that the formula to calculate simple interest is given by

Simple Interest = P x R x T/100

So, the intrest at the end of the first year ₹(100 x 8 x 1)/100 = ₹ 80.

The interest at the end of the 2nd year = ₹(1000 x 8 x 2)/100 = ₹160

The interest at the end of the 3rd year = ₹(1000 x 8 x 3) /100 = ₹ 240

Similarly, we can obtain the interest at the end of the 4rth year, 5th year and so on.

So, the intrest (in ₹) at the end of the 1st,2nd, 3rd

............ year's respectively are 80, 160, 240. ...........

It is an AP where a = 80 and d = 80

The interest at the end of 30 years will be a_30.

a_30 = a + (30 - 1)d = 80 + 29 x 80 = 2400

Therefore, the interest at the end of 30 years will be ₹ 2400.