The probability of picking the first senior is [tex] \frac{5}{8} [/tex]
The probability of picking the second senior is [tex] \frac{4}{7} [/tex]
The probability of picking the third senior is [tex] \frac{3}{6} [/tex]
The probability of picking three senior is
[tex] \frac{5}{8} [/tex]×[tex] \frac{4}{7} [/tex]×[tex] \frac{3}{6} [/tex]=[tex] \frac{5}{28} [/tex]