Originally Posted by AngryPixie

Barny

Drop this into Excel to give you the probability of getting exactly 3 successes from 5 trials with a 35% chance of success on each trial.

=BINOM.DIST(3,5,0.35,FALSE)

You'll get 18.11%

If you wanted to know the chance of getting up to 3 successes (not exactly 3 successes) replace the FALSE with TRUE.