What is the rignt interview time for each, communications homework help

I am going to give you three examples and you give me the appropriate length for each interview and why it should be kept to that length.

1. An interview with a witness to a house fire used in conduction with a reporter’s on set report.

2. An interview with an expert regarding the Gulf oil spill. This will be used in a 30 minute special for local television.

3. A stand-alone interview with a correspondent regarding the day’s military activity in the Iraq war.