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Finding the Fourth Proportional to 129.42, 194.15 and 81.66

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Solution

The fourth proportional to 129.42, 194.15 and 81.66 is: 122.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.42 : 194.15 = 81.66 : x
  2. Step 2: Convert to fraction form
    129.42/194.15 = 81.66/x
  3. Step 3: Cross multiply
    129.42x = 194.15 × 81.66
  4. Step 4: Simplify right side
    129.42x = 15,854.29
  5. Step 5: Solve for x
    x = 15,854.29/129.42
  6. Step 6: Final answer
    x = 122.50

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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.