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:
320m
Step-by-step explanation
a rectangle has four sides, two pairs of identical sides. So two sides are 16. So that adds up to 32. Perimeter is all sides added together. so it has to add up to 72. 72 minus 32 is 40, so two of the sides have to be 40. Area is length times width, so 16 times 20, which is 320.
B. 24 square meters. Length times width times height
Notice that we can simplify both numerator and denominator of our rational function. In the numerator we have a quadratic expression of the form

. To to simplify it, we are going to find tow numbers that add to 2 and multiply to -8; those numbers are 4 and -2.

In the denominator we have a difference of squares:

Now we can rewrite our function:

From the simplified form of our rational function we can infer that its graph has two vertical asymptotes at

and
We can conclude that the graphic of our rational function is:
Well lets see. You have a total of 52 marbles. So all you would have to do would be to find the percent of 52 out of 60. This sounds confusing and I may not be completely right but I hope you give it a shot!