A alone can complete a work in 30 days while B alone can complete the same work in 20 days. In how many days both working together can complete the same work?
A train is running at a speed of 99 km/h. If the train is 565 m long, then what will be the time (in seconds) taken by it to cross a 975 m long tunnel?
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