Final answer:
The number of boys enrolled at Welis College in 2012 was 33.
Step-by-step explanation:
To find out how many boys were enrolled at Welis College in 2012, we can set up an equation based on the given information:
Let's assume the number of boys enrolled in 2012 is 'x'.
According to the ratio of boys to girls being 3:7, the number of girls enrolled in 2012 would be 7x.
We are also given that there were 200 more girls than boys in 2012, so we can set up the equation: 7x - x = 200
Simplifying the equation, we get 6x = 200. Dividing both sides by 6, we find x = 33.33. Since the number of boys must be a whole number, we round down to the nearest whole number, which is 33.
Therefore, the answer is 33 boys (option A).