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Finding the Fourth Proportional to 129.29, 178.39 and 76.81

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Solution

The fourth proportional to 129.29, 178.39 and 76.81 is: 105.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.29 : 178.39 = 76.81 : x
  2. Step 2: Convert to fraction form
    129.29/178.39 = 76.81/x
  3. Step 3: Cross multiply
    129.29x = 178.39 × 76.81
  4. Step 4: Simplify right side
    129.29x = 13,702.14
  5. Step 5: Solve for x
    x = 13,702.14/129.29
  6. Step 6: Final answer
    x = 105.98

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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.