Question

Radhika deposited a sum of ₹ 11000 in a bank for 4 years at an interest rate of 7.5% per annum. Find the interest earned by her after
4 years.

Answer 1

According to the given question

Intersect per year =10,000×5 %

=10,000×  

100

5

​

 

=500

Now,

Amount in I  

st

 years =10,000

Amount in 2  

nd

 year =10,000+intersect

=10,000+500=10,500

Amount in 3  

rd

 year =10,500+Intersect

=10,500+500=11,000

Then our series becomes  

10,000,10,500,11000..

This is an AP

where a=10,000

d=10,500−10,000=500

time (n)=15 year

Then,

Amount in 15  

th

 year =a+(n−1)d

=10,000+(15−1)×500

=10,000+14×500

10,000+7000

17,000

Thus amount in 15  

th

 year in Rs.17,000

Amount of per 20 year =a  

n

​

 

=a+(n−1)d

10,000+(21−1)×500

10,000+10,000

20,000

Thus, the amount in 20  

th

 years is  

Rs.⇒20,000/−

Hence, this is the answer.  

Answer 2

Answer:

Interest=$3300