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Mathematics > Standard Multiple Choice
Read the following SAT test question and then click on a button to select your answer.
The stopping distance of a car is the number of feet that the car travels after the driver starts applying the brakes. The stopping distance of a certain car is directly proportional to the square of the speed of the car, in miles per hour, at the time the brakes are first applied. If the car’s stopping distance for an initial speed of 
miles per hour is 
feet, what is its stopping distance for an initial speed of 
miles per hour?
Hint
The stopping distance is directly proportional to the square of the initial speed of the car. If 
represents the initial speed of the car, in miles per hour, and 
represents the stopping distance, you have that the stopping distance is a function of 
and that 
, where 
is a constant.
represents the initial speed of the car, in miles per hour, and 
represents the stopping distance, you have that the stopping distance is a function of 
and that 
, where 
is a constant. Since the car’s stopping distance is 
feet for an initial speed of 
miles per hour, you know that 
, and the car's stopping distance for an initial speed of 
miles per hour is 