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Finding the Fourth Proportional to 129.74, 178.95 and 86.09

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Solution

The fourth proportional to 129.74, 178.95 and 86.09 is: 118.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.74 : 178.95 = 86.09 : x
  2. Step 2: Convert to fraction form
    129.74/178.95 = 86.09/x
  3. Step 3: Cross multiply
    129.74x = 178.95 × 86.09
  4. Step 4: Simplify right side
    129.74x = 15,404.91
  5. Step 5: Solve for x
    x = 15,404.91/129.74
  6. Step 6: Final answer
    x = 118.74

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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.