A pipe can fill a tank in 6 hours and another pipe can empty the tank in 12 hours. If both the pipes are opened at the same time, the tank can be filled in
Answer & explanation
Correct answer: option 2
The following chart has to be made first:
Efficiency of A = 2
Efficiency of B = -1
Efficiency of A + B = 1
Thus, it will take 12 hours for the cistern to be filled:
\(\frac{12 }{1 }\) = 12 hours