We are told that the ratio of male students to female students is 3:4. If there are 18 male students, then the number of female students must follow the same ratio. That is:
[tex]\frac{3}{4}=\frac{18}{x}[/tex]Where "x" is the number of female students. To determine "x" we multiply both sides by "x", we get:
[tex]\frac{3x}{4}=18[/tex]Now we multiply both sides by 4/3, we get:
[tex]x=18\times\frac{4}{3}[/tex]Solving the operations we get:
[tex]x=\frac{72}{3}=24[/tex]Therefore, there are 24 female students.
