Question

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

were to have four children altogether? (You may want to use a tree diagram to construct the sample space.)
The probability is
(Type an integer or a simplified fraction.)

Answer 1

Answer: 0.3125.

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