A teacher wants to investigate whether listening to music while taking a math test increases scores. He instructs half of his 36 students to listen to music while taking a test and the other half to not listen to music during the test. To
determine who listens and who does not, the teacher identifies the two students who scored highest on the last test and randomly instructs one to listen to music and one to not. The teacher does the same for the next two highest-
scoring students and continues in this manner until each student has their instructions. Which of the following best
describes this plan?

option 1

data plot with   3 dots over 33, 1 dot over 34, 2 dots over 35, no dot over 36, 1 dot over 37, 2 dots over 38, 4 dots over 39, and 2 dot over 40.

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."