Question

A man deposited Rs. 10000 in a bank at rate of 5% simple interest annually. Find the amount in 15^th year since he deposited the amount & also calculate the total amount after 20 years ?

Answer 1

Given sum = 10000
Rate of interest = 5%
Interest after one year = (10000*5*1)/100 = 500
So amount after one year = 10000 + 500 = 10500
Again amount after two years = 10000 + 2* 500 = 10000 + 1000 = 11000
Again amount after thrr years = 10000 + 3* 500 = 10000 + 1500 = 11500
and so on.
Now it forms an AP and the seroes is: 10000, 10500, 11000, 11500,........
Now first term a = 10000 and common difference d = 500
Now 15th term = a+ (15-1)*d
= 10000 + 14*500
= 10000 + 7000
= 17000
So amount in 15th year = 17000 rupees
Now again amount after 20 years = 10000 + SI for 20 years
= 10000 + (10000*5*20)/100
= 10000 + 100*100
= 10000 + 10000
= 20000 rupees