A 450 meter long train crosses a bridge 650 meters long in 36 seconds. What is speed (in km/hr) of the train? 

There are three taps of diameter 2 cm, 3 cm and 4 cm, respectively. The ratio of the water flowing through them is equal to the ratio of the square of their diameters. The biggest tap can fill an empty tank alone in 81 min. If all the taps are opened simultaneously, then how long will the tank take (in min) to be filled?

If shopkeeper sold the mobile for Rs.15000 and then he gets some loss. If he sold the same mobile at Rs.19200 and then he gets profit is double of loss. Find the cost price of the mobile?

A fruit seller had some oranges and apples. He sold 20% oranges to A, 40% of remaining to B and had 48 oranges left. Similarly, he sold 40% apples to A, 100 apples to B and had 10% apples left. Find the total number of apples and oranges that the shopkeeper had initially.

Find the average of all prime numbers between 30 and 50.

If x²+y²+z² = xy + yz + zx, then the value of $${3x^4+7y^4+5z^4}\over{5x^2y^2+7y^2z^2+3z^2x^2} $$ is

Study the graph carefully and answer the following questions.

The production of State D in 1993-94 is how many times its production in 1994-95 ?