hada_madrina_ratios

import collections
import random

# 1D6
dice = [1, 2, 3, 4, 5, 6]

# rolls a 3D6
roll = lambda x: sum([random.choice(dice) for _ in range(x)])

# roll 1000 times a roll 3D6
rolls = collections.Counter([roll(3) for _ in range(1000)])

# ratio of success and fails
success = sum(times for face, times in rolls.items() if face < 12)
fails = sum(times for face, times in rolls.items() if face >= 12)

print(f'The chance of success is: {success / 10:.02f}')
print(f'The chance of fails is: {fails / 10:.02f}')