Cool Roofs by David Feeley
1 answer:
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Answer:
86.7%.
Explanation:
Considering the diagram, the path of the tip of the blades is a circle.
Hence, determine the circumference of the circle.
C = 2πr = 2π * 3 ft = 6π ft.
Then determine how long the blade edges are all together.
6 in * 5 blades = 30 inches
Therefore, to determine the fraction of the circumference of 30 inches, convert circumference to inches
6π ft * (12 in ÷ 1 ft) = 72π in.
Hence, the probability of Gerald’s randomly timed shot hitting a blade of the windmill
=> 30 ÷ 72π
=> 30 ÷ [72 * (22/7)]
= 13.3%.
Finally, the probability of his shot getting past the blades is then 100 – 13.3 = 86.7%.
