1. There are two given sets, the first one with n elements and the second one with m elements. In how many ways can you rearrange all the elements, so that the first p elements are from the first set, and the last q elements are from the second set?

Is my solution correct?

2. How many different n digit numbers can be made with the numbers 3 and 5?

Is the solution solely 2^n, or 2^n - 2 (without counting the n digit 333...3 and 555...5)? The 3 AND 5 confuses me. Do both 3 and 5 have to appear in the number?

Thanks in advance.