Explanation for Question 13 From the Math (Calc) Section on the Official Sat Practice Test 6
Question 13 asks us the function H defined by H of T is equal 2 to a times T plus B, 3 where a and B are Constance models, the height and centimeters of the flower 4 after T days of growth during the time period in which the growth is 5 approximately linear, what does a represent? 6 Okay, so we've got H of T is equal to a T plus B, 7 and just in very generic math terms, we should know that a is the 8 slope in this turn or in this, 9 um, in this expression, it's how fast the graph is growing. 10 But what exactly is the graph showing here? 11 It's showing sunflower height over time. 12 So a is showing how fast the sunflower height is changing over time. 13 Let's look through the answer choices and see if any correspond with that understanding 14 of the slope. So we have a, 15 the predicted number of centimeters to sinful our growth each day during the period. 16 Okay. So that is actually going to be our answer because the number 17 of centimeters is the growth rate. It's not referring to the overall predicted height, 18 like answer choices, B and C, um, 19 suggest because the height is actually going to be just the Y 20 values here. The rise of a run, 21 the slope is going to be the number of centimeters gained over 22 the number of days. It won't be the height gained over 23 the days, essentially. 24 So for that reason, we can cross out B and C D the predicted 25 total increase in the height of the sunflower in centimeters, 26 during the period. The reason that this one is incorrect, 27 because it refers to the total increase. 28 A slope is just taking a snapshot of one second. 29 The slope units are going to be in days. 30 So it's talking about the rate of growth per each day. 31 On average, it's not going to be the total increase over multiple days 32 during that whole period. So for that reason, 33 we can select ASR.