The simple interest on a certain sum for 3 years is ₹1080 and the compound interest on the same sum at the same rate for 2 years is ₹741.60. Find :

(i) the rate of interest

(ii) the principal.

In what time will ₹2400 amount to ₹2646 at 10% p.a. compounded semi-annually?

The population of a city is 320000. If the annual birth rate is 9.2% and the annual death rate is 1.7%, calculate the population of the town after 3 years.

The cost of a car, purchased 2 years ago, depreciates at the rate of 20% every year. If its present worth is ₹315600, find :

(i) its purchase price

(ii) its value after 3 years.