The total number of student is
[tex]15+13+22=50[/tex]
The number of 7th-grade boys is
[tex]=6[/tex]
The probability of 7th grade boys will be gotten using the formula
[tex]Pr(7th\text{ grade boys)=}\frac{Number\text{ of 7th grade boys}}{\text{total number of students}}[/tex]
Thus, we will have
[tex]Pr(7th\text{ grade boys)}=\frac{6}{50}=\frac{3}{25}[/tex]
Hence,
The total number of the students will be = 3/25
