Problem
In a class of 25 students, 16 have a brother and 10 have a sister. There are 6 students who have a brother and a sister. What is the probability that a student chosen randomly from the class has a sister?
Solution
Step 1 ：Number of students with both brother and sister: 6
Step 2 ：Number of students with only sister: 10 - 6 = 4
Step 3 ：Total number of students with sister: 6 + 4 = 10
Step 4 ：P(student has sister) = \(\frac{10}{25}\)
