math
posted by Jamal .
What is the probability of guessing 70 out of 100 multiple choice questions correct when there are 4 choices per question?

prob of being right is 1/4
prob of guessing wrong is 3/4
so prob of guessing 70 out of 100 correct is
C(100,70)*(1/4)^70*(3/4)^30
= 3.763*10^21
we are dealing with very large and very small numbers here, and I had to "trust" my calculator.