Final answer:
The percentage of students who wore a costume is calculated by dividing the number of students who wore a costume by the total number of students and then multiplying by 100, resulting in 72%.
Step-by-step explanation:
To calculate the percentage of students who wore a costume, you would use the formula percentage = (part/whole) × 100%
Total number of students = students who wore costumes + students who did not = 360 + 140 = 500
The percentage of students who wore a costume = (students who wore costumes / total number of students) × 100%
= (360/500) × 100% = 0.72 × 100% = 72%
Therefore, 72% of the students wore a costume on costume day.