A pipe can fill a cistern in 12 minutes whereas the cistern when fill can be emptied by a leak in 18 minutes. When both pipes are opened, find when the cistern will be full?\nOptions:\n(A) 17\n(B) 16\n(C) 70\n(D) 36\n(E) 12 Stream of consciousness first, then make a decision:
User
1/12 - 1/18 = 1/36\n36 minutes
Thus, the answer is (D).
Assistant