Question : Pipes A and B can fill a tank in 36 hours and 48 hours, respectively. Both pipes are opened together for 9 hours and then A is closed. Pipe B alone will fill the remaining part of the tank now in:

Option 1: $20 \frac{1}{2}$ hours

Option 2: $25$ hours

Option 3: $27$ hours

Option 4: $24$ hours

Question : Two pipes P and Q can fill a cistern in 12 and 15 minutes respectively. Both are opened together, but at the end of 3 minutes, P is turned off. In how many more minutes will Q fill the cistern?

Option 1: $7$ minutes

Option 2: $7\frac{1}{2}$ minutes

Option 3: $8$ minutes

Option 4: $8\frac{1}{4}$minutes

Question : Pipes P and Q can fill a tank in 18 and 27 minutes, respectively, whereas pipe R can empty the full tank in 54 minutes. P and Q were opened together for 6 minutes and then closed and R was opened. The tank was emptied by R alone in:

Option 1: 35 minutes

Option 2: 45 minutes

Option 3: 30 minutes

Option 4: 40 minutes

Question : Pipes A and B can fill a tank in 18 minutes and $22 \frac{1}{2}$ minutes, respectively while pipe C can empty the full tank in 12 minutes. A and B are opened together for 6 minutes and then closed. Now C is opened. C alone will empty the tank in ____.

Option 1: $5$ minutes

Option 2: $8 \frac{2}{5}$ minutes

Option 3: $7 \frac{1}{5}$ minutes

Option 4: $6$ minutes

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