Question

3 pumps, working 6 hours a day, can empy a water tank in 2 days. How many hours a day must 9 pumps work to empty the same tank in 1 day?

Answer 1

`3\ pumps\ work\ 6\ hours\ so\ summing\ work\ each\ of\ them\ they\ work:\\ 3*6=18hours\ in\ one\ day\\\\ 18*2\ hours\ is\ needed\ to\ empty\ water\ tank\ in\ 1\ day\\\\ 9*x\ hours\ is\ needed\ to\ empty\ water\ tank\ in\ 1\ day,\\ where\ x-\ number\ of\ hours\ during\ which\\ every\ of\ 9\ pumps\ work\ in\ one\ day\\\\ Making\ ratio:\\ 18*2\ hours-1\ days\\ 9x\ hours-\ 1\ day\\\\ 36=9x\ \ |:9\\ x=4\ hour\\ 9\ pumps\ must\ work\ 4\ hours\ per\ day\ to\ empty\ water\ tank\ in\ one\ day.`