Remember that the difference between census and a sample survey is that in a census you take all the people of population in consideration in the study, and in the sample survey you take a part of that population in consideration to survey.
SO here if you check the problem it says that "in a recent poll, Pew reserchers found that 47% OF AMERICAN ADULT RESPONDENTS"
that is the population of the study that you want to focus, but there are a billion of american adult in US right? so its impossible that this company Pow Research made a census if you consider that a billion of people in US is almost infinite number for a company with a finite number of employees.
Also remember that a company has a budget to consider every month or every year, so to make a census or a sample survey it takes time and money, just to survey 10 people in a streeth of US cost money so if you want to reduce cost you might need to do a sample survey instead of a census.
Question 2: D
Question 1: C
Question 3: B
Question 4: C
Solve the system by the elimination method.
2a + 3b = 6
5a + 2b - 4 = 0
multiply thru the top equation by 2
Multiply thru the bottom equation by 3
4a + 6b = 12
15a+ 6b = 12
Subtract and solve for "a":
11a = 0
a = 0
Solve for "b" using 2a + 3b = 6
2*0 + 3b = 6
b = 2
