Who is correct and why? •A. Kevin is correct. Amy did not regroup properly.

•B. Amy is correct. Kevin did not regroup properly.

•C. Kevin is correct. Amy did not line up the decimals correctly.

•D. Amy is correct. Kevin did not line up the decimals correctly.

the answer is D. Amy is correct. Kevin did not line up the decimals correctly.

- "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."