Explanation for Question 29 From the Math (Calc) Section on the Official Sat Practice Test 6
Question 29 reads a motor power's a model car. 2 So that after starting from rest, the car travels S inches and T seconds, 3 where S is equal to 16 T times the square root of T, 4 which of the following gives the average speed of the car in inches per 5 second, over the first T seconds after it starts. 6 Okay. So this right here is giving us the number 7 of inches traveled in T seconds. 8 And we're trying to find the average speed. 9 So in order to get that average speed is going 10 to be equal to the distance over time. 11 And this makes sense if you think about it physically, right? Like if you're 12 driving a car, your average speed is just going to be how far you've 13 moved, divided by the amount of time that it took you to move. 14 So for example, that's what it means when you say mile per hour, 15 um, that's really an average speed. So if you drove 60 miles in one 16 hour, your average speed would be 60 miles per hour. 17 So we're just trying to find the distance over the amount of time. 18 And to get that we know that the distance is 16 T route T 19 and time is just T just a variable. 20 So average speed is going to be just 16 21 to root T over T and we can cross those teas out and then 22 we're left with 16 root tea. 23 That's going to be answer choice B.