How long will it take a crew to clean a building with 78 windows if they clean 26 windows in an hour?
A man has to clean a window at a height of 5 m on a building. He needs to reach a point 1.3m below the window to clean it. What should be the length of the ladder that he should use which, when inclined at an angle of 60o to the horizontal, would enable him to reach the required position?