Two trains are moving in the same direction at the speed of 23 km/hr and 77 km/hr. The time taken by faster train to cross a man sitting in the slower train is 40 seconds. What will be the length (in metres) of the faster train?
A regular square pyramid has side of its base 20 cm and height 45 cm is melted and recast into regular triangular pyramids of equilateral base of side 10 cm and height 10√3 cm. What are the total numbers of regular triangular pyramid?