A Sonar of a ship sends sounds waves of speed 1600 m/s. These waves are reflected back by the ocean floor in 4 seconds. Find the depth (in m) of the ocean floor.
A grocer had 1600 kgs of wheat. He sold a part of it at 20% profit and the rest at 12% profit, so that he made a total profit of 17%. How much wheat (in kg) did he sell at 20% profit?