Question

A person deposited Rs 10,000 in a bank at 5% interest compounded annually. After 5 years the rate of interest was 6% and after 4 more years the rate of interest was 7%.Find the amount after 12 years?

Answer 1

Answer: 20000rs

Step-by-step explanation:  According to the given question

Intersect per year =10,000×5 %

=10,000×1005​

=500

Now,

Amount in Ist years =10,000

Amount in 2nd year =10,000+intersect

=10,000+500=10,500

Amount in 3rd 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 15th year =a+(n−1)d

=10,000+(15−1)×500

=10,000+14×500

10,000+7000

17,000

Thus amount in 15th year in Rs.17,000

Amount of per 20 year =an​

=a+(n−1)d

10,000+(21−1)×500

10,000+10,000

20,000

Thus, the amount in 20th years is

Rs.⇒20,000/−

Hence, this is the answer.