Which of the following is best modeled using a linear regression equation, `y= ax+b,` where ` a lt 0`?

Options

A.
B.
C.
D.

Answer

C

Explanation

A regression equation is the equation of the line (or curve) that best fits the data. A linear regression is used to model data that follows the path of a straight line. In the equation given, a represents the slope of the linear regreswsion (the line of best fit), so you are looking for data that is linear and is decreasing, or falling from left to right, which happens with a is negative, or as the question states, when `a lt 0.` You can eliminate (A), which is a quadratic curve, and (D), an exponential cuirve. You can also eliminate (B) because it is increasing (rising from left to right) instead of decreasing (falling from left to right). (C ) is correct.