A pipe can fill a tank in 18 hours. In how much time (in hours) will another pipe operating at one-third the efficiency of the first pipe fill a tank whose capacity is 50% of that of the first tank?

27

A+ = 18 hrs,

Given, 

A : B = 3 : 1,  (Efficiency)

⇒ Total capacity = 3 x 18 = 54 units,

⇒ Time required for B to fill 50% of the tank = \(\frac{54/2}{1}\) = 27 hrs.