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Finding the Fourth Proportional to 129.21, 178.28 and 101.78

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Solution

The fourth proportional to 129.21, 178.28 and 101.78 is: 140.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.21 : 178.28 = 101.78 : x
  2. Step 2: Convert to fraction form
    129.21/178.28 = 101.78/x
  3. Step 3: Cross multiply
    129.21x = 178.28 × 101.78
  4. Step 4: Simplify right side
    129.21x = 18,143.94
  5. Step 5: Solve for x
    x = 18,143.94/129.21
  6. Step 6: Final answer
    x = 140.42

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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.