Ellen plans to have two children but doesn't know if they are boy-boy, girl-girl, or boy-girl. What is the probability that she will have two girls?

0.25

0.5

0.75

1.00

I know the answer is. 25 but how do you get that answer?

You can have a girlboy boygirl boyboy girlgirl and one of those answers iss out of 4 and 1/4 is. 25

There are four ways in which the genders of the children may be arranged. In addition to those already given above is girl-boy. Among the four, there is only girl-girl. Thus, the probability that Ellen will have two girls is 1/4 or 0.25.