A class of 15 students is about to sit a statistics examination....

A class of 15 students is about to sit a statistics examination. They will subsequently be listed in descending order by reference to the marks scored. Assume that there are no tied positions with two or more students having the same mark.

Required

Calculate the following.

1. The number of different possible ordering for the whole class
2. The number of different possible results for the top three places
3. The number of different possible ways of having three people taking the top three p