A “strong positive association” means that as one variable increases, the other one increases. This will be shown as a line that angles through the graph from the lower left to the upper right. These scatterplots don’t have any lines of best fit drawn on them, so imagine the line that would go through most of the points on each graph. In (A), the points are all over the place, so no line of best fit can even be drawn. Eliminate (A). In (B), the line that hits most of the points would go from the upper left to the lower right. This is a negative association, not a positive one, so eliminate (B). In (C), the line would go straight across, parallel to the x-axis. This is not a positive association, so eliminate (C). The correct answer is (D).

To solve this equation, get ​\( \sqrt[]{x} \)​by itself. ​\( \sqrt[]{x} \)​= 16, so square both sides: (​\( \sqrt[]{x} \)​)² = 16², so x = 256. Choice (D) is correct.

To figure out how much you need to add to 2.74 to get to 4.22, take 4.22 − 2.74 on your calculator. The difference between the two numbers is 1.48. This increase reflects the same number, t, added to each of the four numbers on the list. Divide 1.48 by 4 to find that t = 0.37, which is (D).

Solve the first inequality by subtracting 6 from each side so that x > -6. You are looking for values that won’t work for x, and x cannot equal -6. Therefore, the answer must be (A). Just to be sure, solve the next inequality by subtracting 1 from each side to get -2x > -2. Divide by -2, remembering to switch the sign because you are dividing by a negative number, to get x < 1. The values in (B), (C), and (D) fit this requirement as well, so they are values for x and not the correct answer.

To solve this equation, use cross multiplication to get (2x)(x + 2) = (x² + 1)(2). Expand the equation to get 2x² + 4x = 2x² + 2. Once you combine like terms, the result is 2x² – 2x² + 4x = 2 or 4x = 2. Solve for x by dividing both sides by 4 to get x = ​\( \frac{1}{2} \)​ , which is (B).