state gov Bihar SSC (BSSC) Inter Level Mock Test 2024 - 25 Quantitative Aptitude Time and Work Pipe and Cistern
An inlet pipe and an outlet pipe are taking to fill and drain a cistern, respectively, for an hour each at a time, starting with the inlet pipe when the cistern is empty. It takes the inlet pipe 15 hours to fully fill the empty cistern, whereas the outlet pipe can drain the filled cistern completely in 21 hours. How many hours will it take for the cistern to be full?
1
105
2
52.5
3
100
4
99