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Finding the Fourth Proportional to 80.67, 120.81 and 78.39

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Solution

The fourth proportional to 80.67, 120.81 and 78.39 is: 117.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.67 : 120.81 = 78.39 : x
  2. Step 2: Convert to fraction form
    80.67/120.81 = 78.39/x
  3. Step 3: Cross multiply
    80.67x = 120.81 × 78.39
  4. Step 4: Simplify right side
    80.67x = 9,470.30
  5. Step 5: Solve for x
    x = 9,470.30/80.67
  6. Step 6: Final answer
    x = 117.40

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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.