# Quantitative Aptitude – Arithmetic – Pipes and Cisterns – A water tank has inlets of two types A ## Slot -2 – Quantitative Aptitude – Arithmetic – Pipes and Cisterns – A water tank has inlets of two types A

A water tank has inlets of two types A and B. All inlets of type A when open, bring in water at the same rate. All inlets of type B, when open, bring in water at the same rate. The empty tank is completely filled in 30 minutes if 10 inlets of type A and 45 inlets of type B are open, and in 1 hour if 8 inlets of type A and 18 inlets of type B are open. In how many minutes will the empty tank get completely filled if 7 inlets of type A and 27 inlets of type B are open?

Suppose inlets of type A fill A liters per minute and type B fills B liters per minute.
So, capacity of tank = 30(10A + 45B) = 60(8A + 18B)
⇒10A + 45B = 16A + 36B
⇒6A = 9B
⇒A = 1.5B
⇒Capacity of Tank = 30(15B + 45B) = 30*60B = 1800 B
Time taken to fill the tank with 7A and 27B, which is 10.5B and 27B, which is 37.5B = 1800 B / 37.5 B = 48 minutes

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