A researcher knows that in spite of the yellow flashing lights and signs announcing "school zone, 20 mph", drivers in front of Elementary School B proceed at a mean speed of 22 mph. The head of the Police Department's Traffic Control Division hypothesizes that having an adult wearing a florescent orange & green vest at the crosswalks in front of School B will decrease the traffic speed from the current mean of 22 mph during critical times. Thus, the comparison mean is = 22 mph. A sample of n = 10 vehicles driving in front of School B is drawn when the orange lights are flashing AND an adult in florescent clothing is at the crosswalk. The Traffic Division's head finds the following traffic speeds:

The speeds (mph) for this sample of ten cars were: 18, 25, 22, 17, 19, 23, 25, 19, 24, 17

Which hypothesis test needs to be employed here?