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Finding the Fourth Proportional to 138.92, 208.49 and 57.78

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Solution

The fourth proportional to 138.92, 208.49 and 57.78 is: 86.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.92 : 208.49 = 57.78 : x
  2. Step 2: Convert to fraction form
    138.92/208.49 = 57.78/x
  3. Step 3: Cross multiply
    138.92x = 208.49 × 57.78
  4. Step 4: Simplify right side
    138.92x = 12,046.26
  5. Step 5: Solve for x
    x = 12,046.26/138.92
  6. Step 6: Final answer
    x = 86.72

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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.