A biased example: Asking students who are in line to buy lunch
An unbiased example: Asking students who are leaving/going to lunch(<em>NOT buying </em><em>lunch</em><em />).
But in this case, the answer choices can be... confusing.
Don't panic! You're given numbers and, of course, your use of logic.
Answer choice A: 100 students grades 6-8
Answer choice B: 20-30 students any <em>one</em> grade<em></em><em>
</em>Answer choice C: 5 students
<em></em>Answer choice D: 50 students grade 8
An unbiased example would be to choose students from <em>any grade.</em> So we can eliminate choices B and D.
Now, the question wants to <em>estimate how many people at your middle school buy lunch.</em> This includes the whole entire school, and if you are going to be asking people, you aren't just going to assume that if 5 people out of 5 people you asked bought lunch, the whole school buys lunch.
So, to eliminate all bias and/or error by prediction, answer choice A, the most number of students, is your answer.
Answer:
d = 2cot(x) or d = 2/tan(x)
Step-by-step explanation:
The vertical distance from the jet to the top of the house represents the opposite side to the 'x' angle, while the horizontal distance, d, represents the adjacent side. Since we do not know the hypotenuse, the tangent and cotangent functions are the preferable choices:

Therefore, the distance 'd' can be expressed as d = 2cot(x) or d = 2/tan(x).
There is one answer.
The intersecting points are (0, 5) just for the extra if you graph them both.