In the following figure, square represents Artists, triangle represents Military officers, circle represents collectors and rectangle represents Fathers. Which set of letters represents collectors who are either military officers or fathers?
9 hrs after a goods train passed a station, another train travelling at a speed of 72 km/hr following that goods train passed through that station. If after passing the station the train overtakes the goods train in 3 hours. What is the speed of the goods train?
A Sonar of a ship sends sounds waves of speed 1000 m/s. These waves are reflected back by the ocean floor in 2 seconds. Find the depth (in m) of theocean floor.