Answer:
65
Step-by-step explanation:
The mean is calculated as
mean = [tex]\frac{total}{count}[/tex]
let x be the mark of the ninth student , then
[tex]\frac{60+40+50+30+80+40+45+40+x}{9}[/tex] = 50 , that is
[tex]\frac{385+x}{9}[/tex] = 50 ( multiply both sides by 9 )
385 + x = 450 ( subtract 385 from both sides )
x = 65
The ninth student has a score of 65
