In a class of 40 students, there are 10 more girls than boys. If the teacher picks one student at random, what is the probability that the chosen student is a girl?
Let's break down this problem step-by-step:

1. We know there are 40 students in total.
2. There are 10 more girls than boys in the class.
3. Let's use 'x' to represent the number of boys in the class. Then, the number of girls would be x + 10.
4. Since there are 40 students in total, we can write an equation: x (boys) + (x + 10) (girls) = 40.
5. Solving for x, we get: x + x + 10 = 40 => 2x = 30 => x = 15.
6. So, there are 15 boys and 25 girls (15 + 10) in the class.
7. The probability of picking a girl at random would be the number of girls divided by the total number of students: 25 girls / 40 students.

Hence, the probability of choosing a girl at random is 25/40 or 5/8.