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Finding the Fourth Proportional to 91.20, 136.65 and 71.86

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Solution

The fourth proportional to 91.20, 136.65 and 71.86 is: 107.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 136.65 = 71.86 : x
  2. Step 2: Convert to fraction form
    91.20/136.65 = 71.86/x
  3. Step 3: Cross multiply
    91.20x = 136.65 × 71.86
  4. Step 4: Simplify right side
    91.20x = 9,819.67
  5. Step 5: Solve for x
    x = 9,819.67/91.20
  6. Step 6: Final answer
    x = 107.67

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.