Yes, I see how that works. I can NOT believe I was so easily confused by some basic algebra! AH! I feel quite ridiculous having stumbled through that the way I had. Thank you so much for your support!
For the question about the friends coming down to attend a football game, I do believe I have to use the equation. . .
There's no simple way of doing this …
the number of spare tickets wil be between 0 and 125 …
you want the probability that it's 4 or 5 or … or 125.
So it's best to calculate the probability that it's 0 or 1 or 2 or 3, and then subtract that from 1.
So, to start you off … what's the probability that it's 0, or 1?