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Choice A is correct. An equation of a line of best fit for data set F can be written in = + the form y abx , where a is the y-coordinate of the y-intercept of the line of best fit and b is the slope. The line of best fit shown for data set E has a 0,12 y-intercept at approximately ^ h. It’s given that data set F is created by 3.9 multiplying the y-coordinate of each data point from data set E by . It follows 0,12 3.9 that a line of best fit for data set F has a y-intercept at approximately ^ ^ hh, 0,46.8 46.8 or ^ h. Therefore, the value of a is approximately . The slope of a line that passes through points ^x1 , y1 h and ^x2 , y2 h can be calculated as y x 2 2 - - y x1 1 . Since the line of best fit shown for data set E passes approximately through the point 12,30 ^ h, it follows that a line of best fit for data set F passes approximately 12,30 3.9 12,117 0,46.8 12,117 through the point ^ ^ hh, or ^ h. Substituting ^ h and ^ h f 7 o 0 r . 2 ^x1 , y 5 1 h .8 a 5 nd ^x2 , y2 h, respectively, in y x 2 2 - - y x1 1 yields 11 1 7 2 - - 4 5 0 6 . . 8 8 5 , which is equivalent 5 t . o 9 12 , or . Therefore, the value of b is approximately , or approximately . =46.8+5.9 Thus, y x could be an equation of a line of best fit for data set F. Choice B is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors. Choice D is incorrect. This could be an equation of a line of best fit for data set E, not data set F. 51 SAT PRACTICE TEST #6 ANSWER EXPLANATIONS SAT ANSWER EXPLANATIONS n MATH: MODULE 2