The vertical line test helps us determine if the given graph is a function or not.If for one value of x there is only one value of y then the graph is a function.
If we draw vertical lines and if the line crosses the graph at one point only then the graph is a function.
If vertical lines are drwn on the given graph it touches the graph at two points and hence fails the vertical line test .The graph is not a function.
This would not be an appropriate sampling technique because it is biased and it would not be fair for 60 students to choose a mascot for a school with 800 students.
