Shyam drives his car 30 km at a speed of 45 km/h and, for the next 1 h 20 m, he drives it at a speed of 51 km/h. Find his average speed (in km/h) for the entire journey.
The angle of elevation of the top of a chimney and roof of the building from a point on the ground are x and 45° respectively. The height of buidling is h metre. Then the height of the chimney,(in metre) is
A pump can fill a tank with water in 1 hour. Because of a leak, it took \(1{1\over3}\) hours to fill the tank. In how many hours can the leak alone drain all the water of the tank when it is full?