7.1.1 Ratio and Proportion (continued) Example 4 Using Properties of Proportions
The ratio of two unknowns in an algebraic equation is determined in this example. To find the ratio of the two unknowns, manipulate the equation so that x and y are together in the form of a ratio. Simplifying yields the proportion = ,
x y
3 2
which includes the ratio x to y .
Example 5 Problem-Solving Application
A proportion with an unknown is solved for the value of the unknown in this application example. The given proportion is = h 3 1 15 . The proportion sets the ratio of the height to the width of a model chair equal to the ratio of the unknown height to the width of a full-size chair. To solve for the unknown height, h , take the cross product of the proportion and solve for h . The solution yields h = 45. The height of the full-size chair is 45 inches.
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