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Finding the Fourth Proportional to 87.78, 131.88 and 81.68

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Solution

The fourth proportional to 87.78, 131.88 and 81.68 is: 122.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.78 : 131.88 = 81.68 : x
  2. Step 2: Convert to fraction form
    87.78/131.88 = 81.68/x
  3. Step 3: Cross multiply
    87.78x = 131.88 × 81.68
  4. Step 4: Simplify right side
    87.78x = 10,771.30
  5. Step 5: Solve for x
    x = 10,771.30/87.78
  6. Step 6: Final answer
    x = 122.71

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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.