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Finding the Fourth Proportional to 129.34, 178.52 and 87.90

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Solution

The fourth proportional to 129.34, 178.52 and 87.90 is: 121.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.34 : 178.52 = 87.90 : x
  2. Step 2: Convert to fraction form
    129.34/178.52 = 87.90/x
  3. Step 3: Cross multiply
    129.34x = 178.52 × 87.90
  4. Step 4: Simplify right side
    129.34x = 15,691.91
  5. Step 5: Solve for x
    x = 15,691.91/129.34
  6. Step 6: Final answer
    x = 121.32

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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.