Pipe A can fill a tank in 22 hours, and pipe B can fill 50% of the same tank in 14 hours. Pipe C can empty the full tank in 14 hours. If all three pipes are opened together at 5:00 am, and pipe C is closed after 3 hours, then at approximately what time will the tank be completely filled?

If P and Q together can complete a piece of work in 15 days and P alone can do it in 45 days, in how many days can Q alone complete that work?

A can lay a railway track between two stations in 16 days and B can do the same job in 12 days. With the help of C, they finished the job in 4 days. In how many days can C alone do the job?