Math Problem Statement

A 1-foot ruler held perpendicular to a flat surface casts a shadow 8" long. At the same time, a pole casts a shadow 18'7" long. What is the height of the pole? Give your answers in feet and inches.

Solution

To solve this problem, we use the principle of similar triangles since the ruler and the pole create proportionate triangles.

Step 1: Extract the given data

  • Height of ruler: 1 foot (12 inches).
  • Shadow of ruler: 8 inches.
  • Shadow of pole: 18 feet 7 inches, which is equivalent to 18×12+7=22318 \times 12 + 7 = 223 inches.
  • Let the height of the pole be hh (in inches).

Step 2: Set up the proportion

The ratio of the height to the shadow is the same for both objects: Height of rulerShadow of ruler=Height of poleShadow of pole\frac{\text{Height of ruler}}{\text{Shadow of ruler}} = \frac{\text{Height of pole}}{\text{Shadow of pole}} 128=h223\frac{12}{8} = \frac{h}{223}

Step 3: Solve for hh

Cross-multiply: h=122238h = \frac{12 \cdot 223}{8} h=334.5inches.h = 334.5 \, \text{inches}.

Step 4: Convert to feet and inches

334.5inches=27feet10.5inches.334.5 \, \text{inches} = 27 \, \text{feet} \, 10.5 \, \text{inches}.

Final Answer:

The height of the pole is 27 feet 10.5 inches.

Would you like a breakdown of the steps?

Related Questions:

  1. What would happen if the ruler was not held perpendicular?
  2. How do we handle units in mixed measurements like this problem?
  3. Could we use this method for objects with curved shadows?
  4. How does the length of the shadow depend on the angle of the sun?
  5. How can we apply this principle to calculate the height of a tree?

Tip: Always ensure units are consistent before solving proportions!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Proportions
Similar Triangles
Unit Conversion

Formulas

Height of ruler / Shadow of ruler = Height of pole / Shadow of pole

Theorems

Similarity Theorem

Suitable Grade Level

Grades 6-8