Correct Answer - Option 1 : 81%
Given:
The ratio of number of teachers and the number of students in a school is 2 : 5
On a particular day 15% of teachers and 20% of students were absent.
Formula used:
Formula of percentage.
X% of Y = XY/100
Calculation:
Number of teachers : Number of students in a school = 2 : 5
Total = 2 + 5 = 7
So, let total number of people (teachers and students) in the class be 700
Total number of teachers = 200
Total number of students = 500
Percent of teachers present = (100 – 15) = 85%
Percentage of students present = (100 – 20) = 80%
Number of present teachers = 85/100 × 200 = 170
Number of present students = 80/100 × 500 = 400
Total number of present people (teachers and students) = 170 + 400 = 570
% of present people = 570/700 × 100
⇒ 81.43% ≈ 81%
∴ % of all (teachers and students) who were present in approx was 81%
