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Finding the Fourth Proportional to 129.39, 178.49 and 76.90

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Solution

The fourth proportional to 129.39, 178.49 and 76.90 is: 106.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.39 : 178.49 = 76.90 : x
  2. Step 2: Convert to fraction form
    129.39/178.49 = 76.90/x
  3. Step 3: Cross multiply
    129.39x = 178.49 × 76.90
  4. Step 4: Simplify right side
    129.39x = 13,725.96
  5. Step 5: Solve for x
    x = 13,725.96/129.39
  6. Step 6: Final answer
    x = 106.09

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.