boy-or-girl-1.py

'''
Boy or girl paradox (version 1).

Mr. Jones has two children. The older child is a girl. 
What is the probability that both children are girls?

Answer: 1/2
'''
import numpy as np

NUMBER_OF_SIMULATIONS = 1_000_000
number_of_favorable_outcomes = 0

np.random.seed(0)

i = 0
while i < NUMBER_OF_SIMULATIONS:

    # Pick a random family
    sorted_children = [
        'boy' if np.random.choice([0, 1]) else 'girl',
        'boy' if np.random.choice([0, 1]) else 'girl'
    ]
    # Make sure the older sibling is a girl
    if sorted_children[1] != 'girl':
        continue

    print(f"Simulation {i + 1}/{NUMBER_OF_SIMULATIONS}")

    # If also the younger children is a girl, the outcome is favorable
    if sorted_children[0] == 'girl':
        number_of_favorable_outcomes += 1

    i += 1

print(f"Estimated probability: {
      number_of_favorable_outcomes/NUMBER_OF_SIMULATIONS}")