A sum of money is invested at 10% per annum compounded half-yearly. If the difference of amounts at end of 6 months and 12 months is ₹ 189, find the sum of money invested.

Rohit borrows ₹ 86000 from Arun for two years at 5% per annum simple interest. He immediately lends out this money to Akshay at 5% compound interest compounded annually for the same period. Calculate Rohit's profit in transaction at the end of two years.

The simple interest on a certain sum of money for 3 years at 5% per annum is ₹ 1200. Find the amount due and the compound interest on this sum of money at the same rate and after 2 years, interest is reckoned annually.

Nikita invests ₹ 6000 for two years at a certain rate of interest compounded annually. At the end of first year it amounts to ₹ 6720. Calculate :

(a) the rate percent (i.e. the rate of growth)

(b) the amount at the end of the second year.