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 : Two pipes A and B can fill a tank in 12 hours and 18 hours, respectively. Both pipes are opened simultaneously. In how much time will the empty tank be filled completely?

Option 1: 9 hours 30 minutes

Option 2: 8 hours

Option 3: 7 hours 12 minutes

Option 4: 10 hours 24 minutes

Question : Pipes A and B can fill an empty tank in 6 and 8 hours respectively, while pipe C can empty the full tank in 10 hours. If all three pipes are opened together, then the tank will get filled in:

Option 1: $4 \frac{4}{23}$ hours

Option 2: $6\frac{1}{5}$ hours

Option 3: $5\frac{5}{23}$ hours

Option 4: $7\frac{1}{2}$ hours

Question : Two pipes can fill a tank in 15 hours and 4 hours, respectively, while a third pipe can empty it in 12 hours. How long (in hours) will it take to fill the empty tank if all three pipes are opened simultaneously?

Option 1: $\frac{50}{7}$

Option 2: $\frac{15}{7}$

Option 3: $\frac{30}{7}$

Option 4: $\frac{20}{7}$

Question : Two inlet pipes can fill a cistern in 10 and 12 hours respectively and an outlet pipe can empty 80 gallons of water per hour. All three pipes working together can fill the empty cistern in 20 hours. What is the capacity (in gallons) of the tank?

Option 1: 360

Option 2: 300

Option 3: 600

Option 4: 900