Pipes and Cisterns - Aptitude Questions and Answers Part 4

16. Three inlets P, Q and R take 6 hours to fill a cistern. After being open for 2 hours together, inlet R  develops a fault and has to be closed. P and Q fill the remaining cistern in 7 hours. How much time would R take to fill the cistern alone?

a. 10 hours
b. 12 hours
c. 14 hours
b. 16 hours

Answer: c. 14 hours

17. There are two taps to fill a tank. Pipe A is three times faster than Pipe B. Both the pipes opened together can fill the tank in 36 minutes. How long will the slower pipe take to fill the tank alone?

a. 81 minutes
b. 108 minutes
c. 144 minutes
d. 192 minutes

Answer: c. 144 minutes

18. Pipe A can fill the tank in 60 minutes while Pipe B does it in 40 minutes. If the tank is empty and Pipe B is opened for the first half while both Pipe A and B are opened for the second half, how long will it take to fill the empty tank?

a. 15 minutes
b. 20 minutes
c. 27.5 minutes
d. 30 minutes

Answer: d. 30 minutes