Graphing technology can help us graph quadratic relationships more efficiently than plotting points and graphing by hand. Go to the Math Tools and open the graphing tool to graph the equation in the situation. Then answer the related question. Josh conducts a performance test for a car. During the test, the car attains a maximum speed of 50 miles per hour. This equation models the test, where x represents time in seconds and y represents the speed in miles per hour:

y = -8x² + 40x.

On your graph, mark the locations that represent when the car was not moving. Assuming that the test was complete when the car came to a complete stop, how long was the speed test?