Answer: 28 students
Step-by-step explanation:
The probability of being a girl is 4/7 which means that the probability of being a boy is 3/7 as the fractions must add up to 1.
Assuming the number of people in class is x then the following expression can be used to solve for it;
[tex]\frac{3}{7} x = 12\\\\3x = 12 * 7\\\\x = \frac{12 * 7 }{3} \\\\x = 28[/tex]