Question 1207516
probability of success is normally p.
q is then the probability of no success.


k is normally x


for your problem, i have:
p = .33
q = 1 - p 
n = 12
x = 9


formula is p(x) = p^x * q^(n-x) * c(n,x)


c(n,x) = n! / (x! * (n-x)!)


for your problem, the formula becomes:


p(9) = .33^9 * .67 ^ (12 - 9) * c(12,9) = .0030709486.


in your terminology, i would get:


n = 12
k = 9
q = .33
(1-q) = .67


formula would become:


p(k) = .33^k * .67^(n-k) * c(n,k)


when n = 12 and k = 9 and q = .33, formula becomes:


p(9) = .33^9 * .67^3 * c(12,9).


same result.