Astudy conducted by researchers from the department of education wanted to know the average debt of college students in the united states. in order to obtain a sample representative of all students, the researchers divided college students into the four classes (freshman, sophomore, junior, and senior) and then took a random sample of students from each class. which sampling method did they use?
a) stratified random sampling
b) systematic random sampling
c) cluster sampling
d) simple random sampling

A) Stratified random sampling

Step-by-step explanation:

Since , the researchers divided college students into the four classes (freshman, sophomore, junior, and senior) and then took a random sample of students from each class.

That means each category is participating in the sample.

It means , they used stratified sampling method where each class denotes a strata.

Here ,  each category participates in researcher's analysis.

Hence, the correct answer is A) Stratified random sampling .

2x^2+5x+17

your welcome. : )

let's first notice, the center of the hyperbola is at the origin, since the focus points are equidistantly 3 units away from the origin, that also means that the distance "c" from the center to either focus is 3.

it should also be notable that, the traverse axis for this hyperbola is vertical, or namely over the y-axis and therefore, the positive fraction will be the one with y-variable.

the traverse "a" component or distance from the center to either vertex is not 2, is more than 2, so we can safely put it at √5 ≈ 2.24.