Final answer:
The probability that a student who has a brother also has a sister is 1.4286.
Step-by-step explanation:
To find the probability that a student who has a brother also has a sister, we can use conditional probability.
The number of students who have a brother is given as 14, and the number of students who have a sister is given as 17.
The number of students who have both a brother and a sister can be found by subtracting the number of students who have no siblings from the total number of students: 25 - 5 = 20.
Therefore, the probability that a student who has a brother also has a sister is 20/14 = 1.4286.