If m is the average of the number of students passed from school Y over all the five
years and n is the average of the number of students passed from all the three schools
in 2018, then m : n is equal to:

For this question, we would have to find the total number of students that passed from school Y

The number of students that passed from school Y: 175+225+254+280+276 = 1210

The average number of students that passed from Y would be 1210/5 = 242

The average number of students that passed from all three schools combined in 2018 would be $$\frac{242+254+362}{3}=\frac{858}{3} = 286$$

Giving us the ratio to be $$242:286$$
$$11:13$$

Therefore, Option A is the correct answer.