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Finding the Fourth Proportional to 129.38, 178.43 and 87.47

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Solution

The fourth proportional to 129.38, 178.43 and 87.47 is: 120.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.38 : 178.43 = 87.47 : x
  2. Step 2: Convert to fraction form
    129.38/178.43 = 87.47/x
  3. Step 3: Cross multiply
    129.38x = 178.43 × 87.47
  4. Step 4: Simplify right side
    129.38x = 15,606.11
  5. Step 5: Solve for x
    x = 15,606.11/129.38
  6. Step 6: Final answer
    x = 120.62

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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.