Python Binomial Probability

import math

nCx = lambda n, x: math.factorial(n) / (math.factorial(x) * math.factorial(n - x))
P = lambda n, x, p: nCx(n, x) * p**x * (1 - p)**(n - k)

n = 10
k = 7
p = .38

print ("Probability of {0} successes given {1} trials: {2}".format(k, n, P(n, 7, p)))