Verified Answer :

Water
lost from pipe per day = 1.5 cups


Water
lost from pipe per 7 days = 1.5*7 cups



                                                    = 10.5 cups


16
cups = 1 gallon


10.5
cups = 16/10.5 gallon

                  
                 =0.656 gallon


So
the pipe is leaking about 0.656 gallon per week.