To find the percentage of passed students in the entire school, you can calculate the weighted average of the percentages based on the number of students in each class.

Here's how you can do it:

Calculate the total number of students in the school:
Total students = 20 + 30 + 40 = 90

Calculate the total number of students who passed in each class:
In the first class, 30% of 20 students passed: 0.30 * 20 = 6 students passed.
In the second class, 50% of 30 students passed: 0.50 * 30 = 15 students passed.
In the third class, 60% of 40 students passed: 0.60 * 40 = 24 students passed.
Calculate the total number of students who passed in the entire school:
Total passed students = 6 + 15 + 24 = 45

Calculate the percentage of passed students in the entire school:
Percentage passed = (Total passed students / Total students) * 100 Percentage passed = (45 / 90) * 100 Percentage passed = 0.5 * 100 Percentage passed = 50%

So, the percentage of passed students in the entire school is 50%.