Earn Better Returns from FD

Find the rate of return from 'd% Rs. f at Rs. m' . (in %)

Oxygenated blood returns from lungs to the heart through :-

In the problem 150, the time taken to return to the ground from the maximum height:

A borrowed Rs. 7000 from bank, after 3 years she Returned Rs. 3000 to the bank, After 5 years from starting she returned Rs. 5450 and settle her account. Find the rate of interest.

Radha borrowed Rs. 3500 from bank and returned Rs. 1500 after 3 years. After 5 years from starting she returned Rs. 2725 and settle her account. What was the rate of interest ?