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Finding the Fourth Proportional to 138.20, 207.46 and 69.80

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Solution

The fourth proportional to 138.20, 207.46 and 69.80 is: 104.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 207.46 = 69.80 : x
  2. Step 2: Convert to fraction form
    138.20/207.46 = 69.80/x
  3. Step 3: Cross multiply
    138.20x = 207.46 × 69.80
  4. Step 4: Simplify right side
    138.20x = 14,480.71
  5. Step 5: Solve for x
    x = 14,480.71/138.20
  6. Step 6: Final answer
    x = 104.78

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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.