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Finding the Fourth Proportional to 129.20, 178.17 and 87.20

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Solution

The fourth proportional to 129.20, 178.17 and 87.20 is: 120.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.20 : 178.17 = 87.20 : x
  2. Step 2: Convert to fraction form
    129.20/178.17 = 87.20/x
  3. Step 3: Cross multiply
    129.20x = 178.17 × 87.20
  4. Step 4: Simplify right side
    129.20x = 15,536.42
  5. Step 5: Solve for x
    x = 15,536.42/129.20
  6. Step 6: Final answer
    x = 120.25

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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.