I must be missing something on this problem, so here is the question:
An NFL quarterback's completion rate is 70%. Find the probability that the quarterback completes 15 of 30 passes during the game.
I know its a geometric distribution problem since it has no set number of trials, and that there are two or three numbers I'm dealing with here, and that's where I stop cause I can't figure it out. Any ideas?
It's not a Geometric Distribution.
What we are looking at is the number of successes in $n$ trials. In this case, its the number of complete passes in $30$ attempts. This is a Binomial Distribution.
So we want the probability of getting $15$ successes out of $30$ trials with $p = 0.7$
The resting probability may look small, but remember you are calculating the probability of exactly $15$, not more or not less