Question

A car is traveling at a steady rate of speed. The points (1, 40) and

(3, y) appear on a graph of the car's distance over time. What is the value
of y?

Answer 1

y=120

Explanation:

After 0 hours, the car will have traveled 0 miles, since it has not yet moved.

We can interpret the point (1, 40) to mean that after 1 hour, the car will have traveled 40 units.

Since the x-axis of a graph that represents data usually represents the independent variable (the number or factor that can change however it wants; it does not depend on any other factors), and we know that in this case, time is the independent variable, we know that the x-axis will represent time.

The y-axis usually represents the dependent variable (the number or factor whose changes depend on the independent variable), and in this case, distance is the dependent variable. So, we know that the y-axis will represent distance.

The point (3, y) means that after 3 hours, the car will have traveled y units.

By dividing distance by time, we can find the speed.

Let's use the point (1, 40).

`(distance)/(time) =speed=\\(40)/(1) =speed=\\40=speed`

So, the car's rate was 40 units per hour.

After 3 hours, how much did it travel? Let's multiply time by speed to find the distance.

`speed*time=distance=\\40*3=distance=\\120=distance`

We have now found that 120 is the distance.

y represents the distance after 3 hours, so y=120.