There are 200 students in Year 10. 110 are boys. There are 250 students in Year 11. 140 are boys. Which year has the greater proportion of boys?

Let P1 and P2 be the proportion of boys in each year.
In order to compare them we should pur the two proportions into simple forms.
P1 = (Number of boys) / (Total number of students)
P1 = 110 / 200 and, simplifying the fraction by 10 we get 
P1 = 11 / 20
Similarily, P2 = 140 / 250 = 14 / 25
Now we need to compare 11/20 with 14/25
In the first fraction, we multiply both the numerator and the denominator by 5 to get
11/20 = 55 / 100 = 55%
Similarily, we multiply the second fraction by 4, getting
14/25 = 56/100 = 56%
Therefore, the first proportion is greater than the other.