What formula do you use?

The hole is a cone and it's asking for the surface so am guessing the top of the hole and so for that it would be a circle. And a surface is also the area of something. so:

To find the area of a circle with the radius, square the radius, or multiply it by itself. Then, multiply the squared radius by pi, or 3.14, to get the area. Or A=πr^2

To find the area with the diameter, simply divide the diameter by 2, plug it into the radius formula, and solve as before.

Hope this helps

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."