গাণিতিক যুক্তি MCQ
A pipe was used to fill a cistern in 10 hours but after working for 7 hours it stopped. another pipe that has the capacity to fill the tank in 20 hours was replaced to fill the rest of the tank. How much time will it take to fill the rest of the tank by the second pipe?
সঠিক উত্তর
6 hours