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Finding the Fourth Proportional to 129.88, 194.70 and 81.76

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Solution

The fourth proportional to 129.88, 194.70 and 81.76 is: 122.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.88 : 194.70 = 81.76 : x
  2. Step 2: Convert to fraction form
    129.88/194.70 = 81.76/x
  3. Step 3: Cross multiply
    129.88x = 194.70 × 81.76
  4. Step 4: Simplify right side
    129.88x = 15,918.67
  5. Step 5: Solve for x
    x = 15,918.67/129.88
  6. Step 6: Final answer
    x = 122.56

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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.