The mean of 20 items is 55. If two items 45 and 30 are removed, what will be the new mean of the remaining items?

The upper part of a tree is broken over by the wind makes an angle of 60 ° with the ground. The distance between the root and the point where top of the tree touches the ground is 25 metres. What was the height (in metres) of the tree? 

From a right cone of height h and with base radius r a cone has been cut of from the centre of the height. The volume of remaining frustum of the cone is.

The difference between simple interest and compound on Rs. 1200 for one year at 10% per annum reckoned half-yearly is:

Sanjay and Jacob start running in opposite directions from the same point at speeds of 7m/s and 5m/s. After 42 minutes, how far would they be from each other?

If the speed of the boat in still water is 20 km / h and the speed of the stream is 5 km / h, then how long will it take for the ferry to travel 100 km with the speed of the stream?

A contractor undertakes to finish a certain work in 124 days and employed 120 men. After 64 days, he found that he had already done 2/3 of the work. How many men can be discharged so that the work may finish in time ?

The figure below is an equilateral triangle with sides of length 6. What is the area of the triangle?