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Finding the Fourth Proportional to 129.78, 194.61 and 68.90

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Solution

The fourth proportional to 129.78, 194.61 and 68.90 is: 103.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.78 : 194.61 = 68.90 : x
  2. Step 2: Convert to fraction form
    129.78/194.61 = 68.90/x
  3. Step 3: Cross multiply
    129.78x = 194.61 × 68.90
  4. Step 4: Simplify right side
    129.78x = 13,408.46
  5. Step 5: Solve for x
    x = 13,408.46/129.78
  6. Step 6: Final answer
    x = 103.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.