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Finding the Fourth Proportional to 138.31, 207.11 and 86.87

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Solution

The fourth proportional to 138.31, 207.11 and 86.87 is: 130.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.31 : 207.11 = 86.87 : x
  2. Step 2: Convert to fraction form
    138.31/207.11 = 86.87/x
  3. Step 3: Cross multiply
    138.31x = 207.11 × 86.87
  4. Step 4: Simplify right side
    138.31x = 17,992.38
  5. Step 5: Solve for x
    x = 17,992.38/138.31
  6. Step 6: Final answer
    x = 130.09

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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.