AccelePrep for the ACT Test 2nd Edition Student Text

204 • S URGE TO S UCCESS ! S CIENCE T EST P REP

A graph with two axes represents the relationship between two variables. There may exist a direct, inverse, or constant relationship. The slope of the line, or the direction of the curve, determines the relationship. A straight line indicates a simple (linear) relationship between two variables. A direct relationship exists when there is an increase in both variables; in such a case, the slope of the line is positive:

STRAIGHT LINES

CLOSER LOOK Here are some common Data Representation questions: 1. Select a conclusion that can be supported by Figure 1. 2. Determine what the slope of a given line represents in Figure 2. ͵Ǥ ”‡†‹…– –Š‡ ”‡•—Ž–• ‰‹˜‡ an assumption or a new situation. 4. Select a statement that is best supported by the data represented in Graph 1. ͷǤ ‡–‡”‹‡ –Š‡ ”‡•—Ž–• based on the difference of time or location. 6. Determine the relationship between the two variables. 7. Determine which conclusion is NOT consistent with the information given in Graph 2. 8. Select an explanation for a given outcome. 9. Identify the LEAST •‹‰‹ϐ‹…ƒ– ƒ••—’–‹‘ made when determining a particular outcome.

Positive Slope

An inverse relationship exists when there is an increase in one variable and a decrease in the other; in such a case, the slope of the line is negative:

Negative Slope

A constant relationship exists when there is a change in one variable and the other remains constant. For instance, the y -value remains unchanged regardless of the increase or decrease in the x -value. The result is a horizontal line, which has a slope of zero.

Zero Slope

A parabola is a curve representing an equation in which, in simplest form, one variable is equal to the square of the second variable multiplied by some constant.

PARABOLIC CURVES

Parabolic Curve

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