Question

on a blueprint, a wall that is 45 feet long is 6 inches long. how long should a girder appear on the blueprint if the girder is actually 30 feet long? a) 2 inches b) 4 inches c) 5 inches d) 9 inches

Explanation:

Step1: Set up the proportion

Let \( x \) be the length of the girder on the blueprint (in inches). The ratio of blueprint length to actual length should be constant. So we have the proportion:
\( \frac{6 \text{ inches}}{45 \text{ feet}} = \frac{x}{30 \text{ feet}} \)

Step2: Cross - multiply and solve for \( x \)

Cross - multiplying gives us:
\( 45x = 6\times30 \)
First, calculate the right - hand side: \( 6\times30 = 180 \)
Then, solve for \( x \): \( x=\frac{180}{45} \)
\( x = 4 \)

Answer:

B) 4 inches