(need both parts and tree diagram sketch included)

(1)A class in probability theory consists of 6 men and 4 women. An exam is given and the students are ranked according to their performance knowing their gender but without knowing their names. Assuming that students obtains a different score (i.e. no two students will obtain the same score).

(a)How many different rankings are possible?

(b)If only 3 students are selected at random, how many different rankings are possible in

this case? Use a tree diagram to find the list of all possible rankings in this case.