Solving Proportions Notes

Name:

Date:

📚 Key Definitions

I Can Statement: I can solve proportions for unknown values.

Success Criteria: I will identify equivalent ratios, set up proportions, and solve for missing variables using cross-multiplication.

Ratio: A comparison of two numbers. Example: 3:4 or 3/4

Proportion: Two ratios that are equal to each other. Example: 3/4 = 6/8

Cross-Multiplication: A method to solve proportions by multiplying diagonally across the equal sign.

Step 1: Write the proportion: 3/5 = x/20

Step 2: Cross-multiply: 3 × 20 = 5 × x

Step 3: Solve: 60 = 5x, so x = 12

Step 4: Check your answer: Does 3/5 = 12/20? ___________

Step 1: Write the proportion:

Step 2: Cross-multiply:

Step 3: Solve for x:

Step 4: Check your answer:

1. Solve: 2/3 = x/15

2. If 5 apples cost $2, how much do 15 apples cost? Set up a proportion and solve.

3. A car travels 120 miles in 2 hours. How far will it travel in 5 hours at the same speed?

In one sentence, explain how to solve for the unknown in a proportion problem: