Final answer:
A roof with a "4 in 12" slope rises 4 inches for every 12 inches of run. Proportions are used to solve for unknown measurements.
Step-by-step explanation:
For instance, if a roof extends 3.5 feet horizontally, you would set up the proportion as 12 inches (1 foot) over x inches (3.5 feet). Then cross-multiply to solve for x: 12 inches/1 foot = x inches/3.5 feet
By cross-multiplying, you would calculate the rise of the roof over the 3.5 feet of run. For example, with a scale factor of 1/4":4' and a scale measurement of 12', the solution would follow: 1 foot/12 inches = 12 feet/x inches.
Again, cross-multiply to find the value of x. This method of setting up proportions is a fundamental skill in solving various types of measurement and geometry problems. Converting units, like turning feet into inches (e.g., 10 feet is equivalent to 120 inches), follows the same principles of proportion.