(1) Time taken by 1st hole to empty the tank alone = 9 min Time taken by 2nd hole to empty the tank alone = 6 min Let the total work = LCM (9, 6) = 18units Work done by 1st hole in one minute =
18
9
= 2 units Work done by 2nd hole in one minute =
18
6
= 3 units Hence, work completed by both holes working together in one minute = 2+3 = 5 units Since total work = 18 units Both will take time =