SOLUTION: A building casts a shadow of 108 ft. Tom, who is 6 ft tall, casts a shadow of 4 ft. About how tall is the building?

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Question 456935: A building casts a shadow of 108 ft. Tom, who is 6 ft tall, casts a shadow of 4 ft. About how tall is the building?
Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
This is a proportion problem.
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If a 6 foot tall object (in this case Tom) casts a 4 foot shadow, a 108 foot shadow will be cast by an object of height that is in the same ratio. Call the height of the building H and you can establish a proportion. Put the heights in the numerators and the shadow lengths in their corresponding denominators to get:
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6%2F4+=+H%2F108
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Solve this by cross multiplying the numerator from the left side with the denominator on the right side and then the numerator from the right side with the denominator on the left side and put an equal sign between the two products. In other words:
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6%2A108+=+4H
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Multiply out the left side to get:
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648+=+4H
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Solve for H (the height of the building) by dividing both sides of this equation by 4 to get:
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648%2F4+=+H
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162+=+H
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The height of the building that will cast a 108 foot shadow when a 6 foot tall object casts a 4 foot shadow is 162 feet.
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Hope this helps you to understand proportions.