If pipe A alone is opened, the tank will be filled in 6 minutes. If pipe B alone is opened, the tank wil emptied in 9 minutes. If both are opened together, in how many minutes will the tank be filled?
A15
B3
C18
D27
Answer:
C. 18
Read Explanation:
Total capacity of tank = LCM[6, 9] = 36
Efficiency of A = 36/6 = 6
Efficiency of B = 36/-9 = -4
Efficiency of A and B = 6 + -4 = 2
Time taken by both the pipes to fill the tank = 36/2
= 18 minute