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Finding the Fourth Proportional to 138.34, 207.05 and 86.81

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Solution

The fourth proportional to 138.34, 207.05 and 86.81 is: 129.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.34 : 207.05 = 86.81 : x
  2. Step 2: Convert to fraction form
    138.34/207.05 = 86.81/x
  3. Step 3: Cross multiply
    138.34x = 207.05 × 86.81
  4. Step 4: Simplify right side
    138.34x = 17,974.01
  5. Step 5: Solve for x
    x = 17,974.01/138.34
  6. Step 6: Final answer
    x = 129.93

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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.