<PRE><B>Question 61080</B>
Time taken by town office well to fill the tank = 18 hrs.
So quantity filled in 1 hr = 1/18 th part of the tank

Time taken by high school well to fill the tank = 22 hrs.
So quantity filled in 1 hr = 1/22 nd part of the tank

When both the wells are open, quantity filled up in 1 hr =1/18 + 1/22
                                             = (11+9)/198 [taking LCD]
                                            = 20/198 part of the tank

So time needed by both the wells to fill the tank = 198/20 hrs
                                                 = 9.9 hrs

                                                = 9 hrs 54 min


Good Luck!!!
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