Question

if parents have 4 kids, what is the probability of the first one being one sex and the next three the other sex?

Explanation:

Step1: Determine the sample space

The sample space for the sex of a child has 2 possibilities (male or female).

Step2: Calculate the probability

Since each child's sex is an independent event, and there are 2 possible outcomes for each child. The probability of the first child being a particular sex (say male or female) is $\frac{1}{2}$.

Answer:

$\frac{1}{2}$