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 : 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 15 hours and 18 hours, respectively. Both pipes are opened simultaneously to fill the tank. In how many hours will the empty tank be filled?

Option 1: $8 \frac{2}{11}$

Option 2: $9 \frac{2}{11}$

Option 3: $7 \frac{2}{11}$

Option 4: $10 \frac{2}{11}$

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