The simple interest on a sum of money will be Rs. 2940 after 12 years. If the principal is increased five times after six years, what will be the total interest after 12 years ?

On a certain sum, the compound interest accrued in the first two years is Rs. 5520 and that in the first three years is Rs. 9576. What is the rate of interest ?

A shopkeepe, bought a cycle at 40% discount on its original price He sold it at a price 50% higher than in the original price What percentage profit did he make ?

Two persons A and B can finish a piece of work in 60 days, while A, B, and C can finish the same work in 40 days. How many days will C alone take to finish the work ?

Two pipes A and B can fill a tank in 80 minutes and 60 minutes respectively. There is also an outlet C. If all the three pipes are opened together, the tank takes 40 minutes to fill completely. How much time will C take to empty the full tank ? (Answer in minutes)

In a stream running at 3kmph. a boat goes 42 km upstream and comes back to the starting point in 306 minutes. What is the speed ol the boat in still water ?9