Re: [OT] Math

Sean Bayan Schoonmaker wrote:
> 
> OK, now hold yer horses:
> 
> I want to know the equation for finding the answer to the original
> question: what is the probability of either exactly four, or four or
> more, hits given each shot has a 1 in 6 chance of hitting.

For exactly 4:

P(4) = 6C4*(1/6)^4*(5/6)^2.

In general, for exactly N out of M hitting, with the probability of a
hit being P(hit) and the probability of a miss being P(miss):

P(N) = MCN*(P(hit))^N*(P(miss))^M

For 4 or more:

P(4 or more) = P(4) + P(5) + P(6)

or

P(4 or more) = 1 - P(3 or less)

That gets a bit complex for larger numbers, but it's at least the only
general equation that I can remember.

MCN here is M choose N (combination notation) or M!/((M-N)!*N!)