Hi there! The answer is 100πcm^2
The radius of a circle can be found by dividing the diameter by 2. In other words : the radius is half of the diameter.
Therefore, the radius of a circle with a diameter of 20 cm is 10 cm.
The exact area of a circle can be found using the following formula:

In order to find our answer, we need to plug in the data from the question.

Hence, the answer is 100πcm^2.
I'd say A. 8000, because you'd get the most answers and the biggest variety in answers for a more accurate sample.
Answer:
40 mph
Step-by-step explanation:
We assume "outbound" refers to the trip <em>to the lake</em>. The ratio of speeds is inversely proportional to the ratio of times, so ...
outbound speed : inbound speed = 4 : 3
These differ by one ratio unit, so that one ratio unit corresponds to the speed difference of 10 mph. Then the 4 ratio units of outbound speed will correspond to ...
4×10 mph = 40 mph
Paul's average speed on the outbound trip was 40 mph.
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The distance to the lake was 120 mi.