The ratio of boys to girls in a class is $7$ to $3$. Among the options below, an acceptable value for the total number of students in the class is

1. $21$
2. $37$
3. $50$
4. $73$

Ratio of boys to girls is 7 : 3
Thus ratio of boys in the class (7 / 10) and ratio of girls in the class (3 / 10) should be integer

here, only 50 satisfies this. 35 : 15 = 7 : 3

by
140 points