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Finding the Fourth Proportional to 129.69, 178.92 and 86.13

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Solution

The fourth proportional to 129.69, 178.92 and 86.13 is: 118.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.69 : 178.92 = 86.13 : x
  2. Step 2: Convert to fraction form
    129.69/178.92 = 86.13/x
  3. Step 3: Cross multiply
    129.69x = 178.92 × 86.13
  4. Step 4: Simplify right side
    129.69x = 15,410.38
  5. Step 5: Solve for x
    x = 15,410.38/129.69
  6. Step 6: Final answer
    x = 118.82

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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.