Quick simulation for a problem from the Advanced Probability class at my school.

blood_type.py

import random # imports
ITER = 100_000 # iteration count

a_guilty = b_guilty = 0 # initialize our counters

for _ in range(ITER):

    # initialize our profiles
    # [has blood type x, is guilty]
    profiles = [[True, 1], [((random.randint(1,10)) == 1), 0]]

    # assign our profiles to a and b randomly
    a, b = ((profiles[0], profiles[1]), (profiles[1], profiles[0]))[random.randint(0,1)]

    if not a[0]: continue # if a does not have blood type x, then skip this iteration

    # update our counters
    a_guilty += a[1]
    b_guilty += b[1]

# finally, print out our results.
print(a_guilty/(a_guilty+b_guilty))