My AP Statistics teacher gave my class two sheets of problems today(first day of class) to see how we could do. I haven't done problems like these for a year or two so I want to make sure I'm on track.

I want to make sure these three in particular are correct:

1.How many ways can 8 members of a family be seated side-by-side in a movie theater if the father is seated on the aisle?

My attempt:

I represented the father as

, I know

and

are the same. Is my answer correct?

2. How many license plate numbers consisting of three letters followed by three numbers are possible when repetition is allowed?

My attempt:

3. How many combinations are possible using the information in problem 7(the above problem) if no repetition is allowed?

My attempt: