If $$ {x+{1\over x}}=3$$ then find the value of $$ {x^2}-{1\over {x^2}}$$:

The ratio of curved surface area and volume of a cylinder is 1 : 7. The ratio of total surface area and volume is 187 : 770. What is the respective ratio of its base radius and height?

From a point P on a level ground, the angle of elevation of the top tower is 30^o.If the tower is 100 m high, the distance of point P from the foot of the tower is:

Hari and Mohan contested a panchayat election. Hari got 52 percent votes and defeated Mohan by a margin of 90 votes. What was the total turnout in the election.

Direction: Study the following graph carefully and answer the questions that follow:
The graph given below represents the number of users of two broadband services A and B across 5 cities P, Q, R, S and T.

What is the total number of users of brand B across all five cities together?

In a regular polygon, the exterior and interior angles are in the ration 1:4.The number of sides of the polygon is

A hollow iron pipe is 21 cm long and its exterior diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weights $$ 8 g/cm^3 $$, then the weight of the pipe ($$ π= {22\over7}$$) is. 

A and B can do a piece of work in 20 days and 12 days respectively. A started the work alone and then after 4 days B joined him till the completion of the work. How long did the work last?