Question : Pipes A, B and C together can fill a cistern in 12 hours. All three pipes are opened together for 4 hours and then C is closed. A and B together take 10 hours to fill the remaining part of the cistern. C alone will fill two-thirds of the cistern in:

Option 1: 60 hours

Option 2: 40 hours

Option 3: 48 hours

Option 4: 50 hours

Question : Three pipes, A, B, and C can fill an empty cistern in 2, 3, and 6 hours respectively. They are opened together. After what time should B be closed, so that the cistern gets filled in exactly 1 hr 15 min?

Option 1: 20 min

Option 2: 45 min

Option 3: 30 min

Option 4: 15 min

Question : Pipes A, B and C can fill an empty tank in $\frac{30}{7}$ hours if all three pipes are opened simultaneously. A and B are filling pipes and C is an emptying pipe. Pipe A can fill the tank in 15 hours and pipe C can empty it in 12 hours. In how much time (in hours) can pipe B alone fill the empty tank?

Option 1: 3

Option 2: 5

Option 3: 6

Option 4: 4

Question : When operated separately, pipe A takes 5 hours less than pipe B to fill a cistern, and when both pipes are operated together, the cistern gets filled in 6 hours. In how much time (in hours) will pipe B fill the cistern, if operated separately?

Option 1: 15

Option 2: 18

Option 3: 10

Option 4: 9

Question : A swimming pool has 3 drain pipes. The first two pipes A and B, operating simultaneously, can empty the pool in half the time that C, the 3^rd pipe, alone takes to empty it.  Also pipe A, working alone, takes half the time taken by pipe B. Together they take 6 hours 40 minutes to empty the pool. The time taken by pipe A to empty the pool, (in hours) is:

Option 1: 15 hours

Option 2: 10 hours

Option 3: 30 hours

Option 4: 7 hours