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 chosen randomly from the class has a sister?


Has a sister 6
Does not have a sister 3

Has a brother 12
Does not have a brother 9

The probability of a student chosen randomly from the class having a sister is:

Number of students with a sister / Total number of students

= 6 / (6 + 3 + 12 + 9)

= 6 / 30

= 0.2

Therefore, the probability is 0.2 or 20%.

To find the probability that a student chosen randomly from the class has a sister, we need to calculate the ratio of the number of students who have a sister to the total number of students in the class.

Number of students who have a sister: 6
Total number of students: 6 + 3 + 12 + 9 = 30

Probability of having a sister = Number of students who have a sister / Total number of students
= 6 / 30
= 1/5
= 0.2

Therefore, the probability that a student chosen randomly from the class has a sister is 0.2 or 20%.