In how many years will be Rs. 2,000 amounts to Rs.2,420 at 10% per annum compound interest ?

At what percent per annum will Rs. 3000 amounts to Rs. 3993 in 3 years if the interest is compounded annually?  

There is 80% increase in amount in 5 years at simple interest. What will be the compound interest of Rs. 20,000 after 3 years at the same rate?

A sum of money becomes eight times in 3 years, if the rate is compounded annually. In how much time will the amount at the same compound rate become sixteen times? 

Rahul plans to buy a scooter for his sister for which he saves Rs. 15625 at the start of every year for 3 year. If the rate of CI is 4% pa. then amount at which he plans to buy the scooter is (in Rs.)

What will be the compound interest (nearest to Rs. 1 on a sum of Rs. 25,000 for 2 years at 12% p.a., if the interest is compounded 8-monthly?

A man invested a certain sum in scheme A at 15% p.a. for 2 years and earned Rs 1950 as simple interest. He increased his sum by Rs. ‘x’ and invested in another scheme B at 10% p.a. C.I. for 2 years and received Rs. 1680 as compound interest. Find the value of ‘x’. 

Surekha borrowed a sum of money and returned it in two equal annual instalments of ₹5,547 each. If the rate of interest was $$7{1\over 2}\%$$ p.a. compounded yearly, then the total interest paid by her was: