Solving Proportions Lecture Notes

Jul 23, 2024

Solving Proportions

Problem Statement

  • Solve the proportion: 8/36 = 10/n
  • Objective: Find the value of n that makes the fractions equivalent.

Methods to Solve the Proportion

Method 1: Equivalent Fractions

  • Concept: The ratios or fractions must remain equivalent.
  • Steps:
    1. Determine multiplier for numerator:
      • 8 * (10/8) = 10
      • This multiplier (10/8) is simplified to 5/4.
    2. Apply multiplier to the denominator:
      • 36 * (5/4)
      • Simplify:
        • 36/4 = 9
        • 9 * 5 = 45
    3. Therefore, n = 45.

Method 2: Ratios and Multipliers

  • Concept: Scaling the numerator and denominator consistently.
  • Steps:
    1. Find the ratio of the denominator to the numerator:
      • 36 / 8 = 4.5 (or simplified as 9/2)
    2. Apply this ratio to the second fraction:
      • 10 * (9/2) = 45
    3. Therefore, n = 45.

Method 3: Cross-Multiplication

  • Concept: Cross-multiplying to find the unknown.
  • Steps:
    1. Set up equation: 8/36 = 10/n
    2. Cross-multiply:
      • 8 * n = 36 * 10
      • 8n = 360
    3. Solve for n by dividing both sides by 8:
      • n = 360 / 8
      • 8 goes into 36 (4 times) = 32 + carry over 4 (40), 40/8 = 5
      • n = 45
    4. Therefore, n = 45.

Method 4: Algebraic Approach

  • Concept: Using algebra to isolate the variable.
  • Steps:
    1. Set up equation: 8/36 = 10/n
    2. Multiply both sides by n:
      • (8/36) * n = 10
    3. Multiply both sides by 36 to isolate n:
      • n = 10 * (36/8)
      • Simplify: 360 / 8
      • n = 45
  1. Therefore, n = 45

Conclusion

  • Regardless of the method used (Equivalent Fractions, Ratios and Multipliers, Cross-Multiplication, or Algebra), the value of n is consistently found to be 45.