Question

Assuming that boy and girl babies are equally likely, what would be Kathy's probability of having at most one daughter if she

Answer 1

Answer: 0.3125.

Step-by-step explanation:

• The chance of having a boy is 0.5,
• the chance of having a girl is also 0.5.

Outcome 1: all boys

boy  boy  boy  boy

0.5 * 0.5 * 0.5 * 0.5 = 0.0625

Outcome 2: first child is a girl, all others are boys

girl   boy   boy   boy

0.5 * 0.5 * 0.5 * 0.5 = 0.0625

Outcome 3: second child is a girl, all others are boys

boy   girl   boy   boy

0.5 * 0.5 * 0.5 * 0.5 = 0.0625

Outcome 4: third child is a girl, all others are boys

boy   boy   girl   boy

0.5 * 0.5 * 0.5 * 0.5 = 0.0625

Outcome 5: fourth child is a girl, all others are boys

boy   boy   boy   girl

0.5 * 0.5 * 0.5 * 0.5 = 0.0625

Therefore,

0.0625 + 0.0625 + 0.0625 + 0.0625 + 0.0625 = 0.0625 * 5 = 0.3125