In a multiple choice test there are 10 queastion and each had 4 choices.

If a student guesses at each of the answer, what is the prob of getting none corrects? /// I just want to prove my answer:

p(X=0)

= 10c0

= 10!/ 0!(10-0)!

= 10!/10!

=1

b.) More than 7 corrects:

10c8 * 10c9 * 10c10

=10!/ 8!(10-8)! * 10!/ 9!(10-9)! * 10!/ 10!(10-10)!

=45 * 10 * 1

=450

*Just wanna know if they are correct!!!tnx