Select the best answer. the web portal aol places opinion poll questions next to many of its news stories. simply click your response to join the sample. one of the questions in january 2008 was "do you plan to diet this year? " more than 30,000 people responded, with 68% saying "yes." you can conclude that
(a) about 68% of americans planned to diet in 2008.
(b) the poll used a convenience sample, so the results tell us little about the population of all adults.
(c) the poll uses voluntary response, so the results tell us little about the population of all adults.
(d) the sample is too small to draw any conclusion.
(e) none of these.

The correct answer is (c) the poll uses voluntary response, so the results tell us little about the population of all adults.

Step-by-step explanation:

You can't conclude (a) because this question hasn't be made to all the Americans.  

You can't conclude (b) because the poll doesn't use any convenience for the selection of the sample

You can't conclude (d) because this is not a poll with a premeditated sample, therefore, the size is inconclusive.  

You can conclude (c) because the poll was available for anyone who voluntary wanted to answer it.

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15