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Lesson 1-4: Ratios and Percentages

Scenario: Class Voting - Analyze election results and survey data!

Duration: 50-65 minutesScenario: Class Voting

Learning Objectives

  • Convert ratios to percentages using the formula: Percentage = (Part ÷ Whole) × 100%
  • Analyze voting results and survey data
  • Use percentages to make predictions and comparisons
  • Solve problems involving percentage calculations

Converting Ratios to Percentages

Class Election Scenario

In a class of 40 students, 18 students voted for Candidate A. What percentage of the class voted for Candidate A?

Percentage Formula: Percentage = (Part ÷ Whole) × 100%

Step-by-Step Solution

Step 1: Identify the part and whole

Part = 18 students (voted for A), Whole = 40 students (total class)

Step 2: Calculate the ratio as a decimal

18 ÷ 40 = 0.45

Step 3: Convert to percentage

0.45 × 100% = 45%

Answer: 45% of the class voted for Candidate A.

Using Percentages for Predictions

School-wide Election

If the entire school has 800 students and the same voting pattern continues, how many students would vote for Candidate A?

Solution: 800 students × 45% = 800 × 0.45 = 360 students

We predict that 360 students in the entire school would vote for Candidate A.

More Percentage Problems

Example 1

What percentage is 25 out of 80?

Solution: (25 ÷ 80) × 100% = 0.3125 × 100% = 31.25%

Example 2

What is 15% of 60?

Solution: 60 × 15% = 60 × 0.15 = 9

Practice Problems

Problem 1

In a survey of 200 people, 120 people said they like pizza. What percentage of people like pizza?

Your calculation:

Problem 2

If 30% of a class of 50 students are boys, how many boys are in the class?

Your calculation: