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Finding the Fourth Proportional to 129.19, 178.28 and 85.61

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Solution

The fourth proportional to 129.19, 178.28 and 85.61 is: 118.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.19 : 178.28 = 85.61 : x
  2. Step 2: Convert to fraction form
    129.19/178.28 = 85.61/x
  3. Step 3: Cross multiply
    129.19x = 178.28 × 85.61
  4. Step 4: Simplify right side
    129.19x = 15,261.87
  5. Step 5: Solve for x
    x = 15,261.87/129.19
  6. Step 6: Final answer
    x = 118.14

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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.