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Finding the Fourth Proportional to 87.78, 131.76 and 81.90

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Solution

The fourth proportional to 87.78, 131.76 and 81.90 is: 122.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.78 : 131.76 = 81.90 : x
  2. Step 2: Convert to fraction form
    87.78/131.76 = 81.90/x
  3. Step 3: Cross multiply
    87.78x = 131.76 × 81.90
  4. Step 4: Simplify right side
    87.78x = 10,791.14
  5. Step 5: Solve for x
    x = 10,791.14/87.78
  6. Step 6: Final answer
    x = 122.93

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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.