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Finding the Fourth Proportional to 138.92, 208.37 and 81.24

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Solution

The fourth proportional to 138.92, 208.37 and 81.24 is: 121.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.92 : 208.37 = 81.24 : x
  2. Step 2: Convert to fraction form
    138.92/208.37 = 81.24/x
  3. Step 3: Cross multiply
    138.92x = 208.37 × 81.24
  4. Step 4: Simplify right side
    138.92x = 16,927.40
  5. Step 5: Solve for x
    x = 16,927.40/138.92
  6. Step 6: Final answer
    x = 121.85

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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.