Question 110969
A building is casting a 100 ft. shadow at the same time that a 5 ft. post is casting a 1 ft. shadow. 
Write a proportion that involves the height of the building, the height of the post, and length of the shadows.
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Let height of the building be "x":
Proportion:
x/100 = 5/1
x = 500 ft
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How high is the building? 
The building is 500 ft. high
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Cheers,
Stan H.