Which expression represents the average of three test scores?

C) is the correct answer

Step-by-step explanation:

In order to find an average, you need to add x, y, and z and then divide them by 3 because there are 3 test scores, and x, y, and z represent the grades for each test. This is why C) x+y+z/3 is correct.

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step-by-step explanation:

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- "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."