Step-by-step explanation:
First, the pizza is 18 inches in diameter, so
![d = 18](https://tex.z-dn.net/?f=d%20%3D%2018)
and, because the radium is half of the diameter,
![r = 9](https://tex.z-dn.net/?f=r%20%3D%209)
<u>Note that the units are inches.</u>
Using the equation
![a = \pi r ^{2}](https://tex.z-dn.net/?f=a%20%3D%20%5Cpi%20%20r%20%5E%7B2%7D%20)
where a is the area of a circle, we know that the area of the whole pizza is approx.254.5 square inches. Divide by 8 to find the area of 1/8 of a pizza. Each slice will have an area of approx. 32 square inches. For a precise result, the answer is
![a(s)= \frac{(\pi \times 9^{2})}{s}](https://tex.z-dn.net/?f=a%28s%29%3D%20%20%5Cfrac%7B%28%5Cpi%20%20%5Ctimes%209%5E%7B2%7D%29%7D%7Bs%7D%20)
where a(s) is the area of a slice of pizza, and s is the total number of slices, given they are equal in size.
Total of the 6 lawna = 10 + 15 + 12 + 15 + 8 + 15 = $75
Given that the mean is $12 for 7 lawns,
Total of the 7 lawns = 12 x 7 = $84
Therefore the 7th lawn is:
$84 - $75 = $9
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Answer: He earns $9 on the 7th lawn. (Answer A)
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12/5 - 3/10 = 24-3 /10 = 21/10
OR 2.1 in decimal form