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Finding the Fourth Proportional to 129.60, 178.85 and 71.39

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Solution

The fourth proportional to 129.60, 178.85 and 71.39 is: 98.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.60 : 178.85 = 71.39 : x
  2. Step 2: Convert to fraction form
    129.60/178.85 = 71.39/x
  3. Step 3: Cross multiply
    129.60x = 178.85 × 71.39
  4. Step 4: Simplify right side
    129.60x = 12,768.10
  5. Step 5: Solve for x
    x = 12,768.10/129.60
  6. Step 6: Final answer
    x = 98.52

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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.