Explanation:

- Pipe Filling:

- Can fill the entire container in 12 hours.

- Rate of filling = 1/12 of the container per hour.

- Pipe Emptying:

- Empties 50% of the container in 10 hours.

- Rate of emptying = 0.5/10 = 1/20 of the container per hour.

- Net Rate of Filling:

- Effective rate when both pipes are open = (1/12) - (1/20).

- Common denominator:

- Convert to same base: (5/60) - (3/60) = 2/60 = 1/30.

- Time to Fill Half the Container:

- Need to fill 1/2 of the container.

- Time = (1/2) / (1/30) = 15 hours.

- Answer Options:

- Option 1: 15 hours

- Option 2: 18 hours

- Option 3: 12 hours

- Option 4: 14 hours

- Option 5: 10 hours

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