A school has only four classes that contain 10, 20, 30 and 40 students respectively. The pass percentage of these classes are 20%, 30%, 60% and 100% respectively. Find the pass % of the entire school.

To find the pass percentage of the entire school, we need to calculate the weighted average of the pass percentages of each class. The weight of each class is determined by the number of students in that class.

Let's calculate:

Pass percentage of Class 1 (10 students, 20% pass rate): 10 students * 20% = 2 students pass

Pass percentage of Class 2 (20 students, 30% pass rate): 20 students * 30% = 6 students pass

Pass percentage of Class 3 (30 students, 60% pass rate): 30 students * 60% = 18 students pass

Pass percentage of Class 4 (40 students, 100% pass rate): 40 students * 100% = 40 students pass

Total number of students: 10 + 20 + 30 + 40 = 100 students

Total number of students who passed: 2 + 6 + 18 + 40 = 66 students

Pass percentage of the entire school: (66 students / 100 students) * 100% = 66%

Therefore, the pass percentage of the entire school is 66%.

The correct answer is D. 66%.

10x20%=2
20×30%=6
30×60%=18
40×100%=40
2+6+18+40=66

2+6+18+40 = 66 ????
How it is possible????