Three girls

We will use the choice function from the random module.

>>> import random

This is a module:

>>> type(random)
<class 'module'>

Use random. and then Tab to see the functions inside the module, from within the Notebook.

We will use random.choice, a function within the random module.

You can check the help with random.choice? in the Notebook.

Here we ask it to choose randomly between the two letters in the string, "HT":

>>> random.choice('HT')
'H'
>>> random.choice('HT')
'T'
>>> random.choice('HT')
'H'
>>> random.choice('HT')
'H'

A coin toss!

Now we have everything we need to solve the problem:

>>> # Make a counter to store how many times we have 3 girls
>>> counter_3girls = 0

>>> # Make 10000 families
>>> for i in range(10000):
...     # Make one family
...     # A counter to store how many girs in this family
...     counter_girls = 0
...     # Have 4 children
...     for j in range(4):
...         coin = random.choice('HT')
...         if coin == 'H':
...             counter_girls = counter_girls + 1
...
...     # Increase counter if this is a 3 girl family
...     if counter_girls == 3:
...         counter_3girls = counter_3girls + 1

>>> proportion = counter_3girls / 10000

>>> proportion
0.2548