To find out how many boys are in the class, we can use the given girl-to-boy ratio of 3 to 7.
First, we add up the parts of the ratio: \[ 3 \text{ (girls)} + 7 \text{ (boys)} = 10 \text{ (total parts)} \]
Next, we can find the value of one part by dividing the total number of students by the total parts in the ratio: \[ \text{One part} = \frac{50 \text{ students}}{10 \text{ parts}} = 5 \text{ students per part} \]
Now we multiply the number of parts for boys by the number of students per part to find the number of boys: \[ 7 \text{ (boys)} \times 5 \text{ (students per part)} = 35 \text{ boys} \]
Thus, there are 35 boys in the class.