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An architect's model of a building uses the scale of 1 inch = 2 1/2 feet. If theheight of the model is 20 inches, how tall will the actual building be?

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We can use a proportion to solve this problem.

Proportions are set up as ratios that are equivalent to each other. For instance, if you were to set up the following ratio:


(1)/(2)=(2)/(4)

We know that this is true. We can also apply algebraic examples.


(1)/(2.5)=(20)/(x)

We can solve for x (the measurement for how tall the building will be) using cross-multiplication and simplification.

Let's cross-multiply the fractions.


1x=50

Then, we divide both sides by 1 to get x by itself.


(1x)/(1)=(50)/(1)

This leaves us with x = 50, which means that the building will be 50 feet tall.

User Yonkee
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