SOLUTION: How many ways can a student select 2 electives from a possible choice of 10 electives?

Algebra ->  Probability-and-statistics -> SOLUTION: How many ways can a student select 2 electives from a possible choice of 10 electives?      Log On


   

Question 1191416: How many ways can a student select 2 electives from a possible choice of 10 electives?
Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

There are 10 choices for the first slot and 10-1 = 9 choices for the next.
That gives 10*9 = 90 permutations.
Since order doesn't matter, we really have 90/2 = 45 combinations.
A group like {A,B} is the same as {B,A}

Answer: 45