Final answer:
Out of 1200 students, if 85% passed, then 15% failed. By calculating 15% of 1200, we determine that 180 students failed.
Step-by-step explanation:
To calculate how many students failed when 85% passed in a school of 1200 students, we subtract the percentage of students who passed from 100% to find the percentage who failed. Then, we apply that percentage to the total number of students.
First, find the failure percentage:
100% - 85% = 15% failed
Next, calculate the number of students who represent this percentage:
(15/100) × 1200 students = 180 students failed
Therefore, 180 students failed out of the 1200 students in the school.