In a class of students, the following data table summarizes how many students have a brother or a sister. What is the probability that a student who does not have a sister has a brother?
Has a brother Does not have a brother
Has a sister 4 7
Does not have a sister 5 11
To find the probability that a student who does not have a sister has a brother, we need to calculate the number of students who do not have a sister and have a brother and divide it by the total number of students who do not have a sister.
From the table, the number of students who do not have a sister and have a brother is 5.
The total number of students who do not have a sister is 5 + 11 = 16.
Therefore, the probability that a student who does not have a sister has a brother is 5/16 or 0.3125.
So, the probability is 0.3125 or 31.25%.