The data is a little bit complex,but you can use the knowledge of vector in the subject of algebra,or you can ultimate the basic Euclidean knowledge,like cosine theorem.In detail,you can list two equation with two variable,and get the answer.but i don't finish calculating it.
Answer: Biased sample
Step-by-step explanation:
This is a biased sample because only students with strong opinions are likely going to volunteer or show interest in representing the school at the board meeting. This sample is a voluntary type sample, and at such the conclusion is not valid. This sample is biased because a group or population of students have a higher or lower sampling probability.
It would be 13... if I did my math right.