Question

Pipes A and B can fill a tank in 18 minutes and 27 minutes, respectively. C is an outlet pipe. When A, B and C are opened together, the empty tank is completely filled in 54 minutes. Pipe C alone can empty the full tank in:

• A. $$14\frac{1}{2}$minutes$
• B. 14minutes
• C. $$13\frac{1}{2}$minutes$
• D. 13minutes

Answer 1

Answer:

$$13\frac{1}{2}$minutes$

Solution: Given: Pipes A and B can fill a tank in 18 minutes and 27 minutes, respectively. When A, B and C are opened together, the empty tank is completely filled in 54 minutes. Calculation: Pipe A's 1 minute's work = 1/18 Pipe B's 1 minute's work = 1/27 Let pipe C's 1 minute's work be 1/C. ⇒ (1/18 + 1/27) - 1/C= 1/54 ⇒ 1/C = 2/27 ∴ Pipe C can alone empty the tank in 27/2 =13 1/2 minutes.