Question

Can somebody answer the unsolved ones ?

Answer 1

There are 15 students in math class.at the begning of class everyone races into class as everyone love maths.the professor takes note of the first 5 students who gets class and ranks them according to the order in which they entred as their top 5 favourite students. in how many different ways could the professor rank their top 5 students using formulla from combinations and permutations