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Finding the Fourth Proportional to 129.69, 194.84 and 81.09

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Solution

The fourth proportional to 129.69, 194.84 and 81.09 is: 121.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.69 : 194.84 = 81.09 : x
  2. Step 2: Convert to fraction form
    129.69/194.84 = 81.09/x
  3. Step 3: Cross multiply
    129.69x = 194.84 × 81.09
  4. Step 4: Simplify right side
    129.69x = 15,799.17
  5. Step 5: Solve for x
    x = 15,799.17/129.69
  6. Step 6: Final answer
    x = 121.82

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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.