Two pipes A and B can fill a tank in 36 hours and 45 hours respectively. If both the pipes are opened simultaneously, how much time will be taken to fill the tank?\nOptions:\n(A) 20 hrs\n(B) 22 hrs\n(C) 23 hrs\n(D) 24 hrs\n(E) 21 hrs Stream of consciousness:
User
1/( 1/36 +1/45) = 180/9 = 20 hrs
Thus, the answer is (A).
Assistant