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Finding the Fourth Proportional to 138.38, 207.48 and 90.56

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Solution

The fourth proportional to 138.38, 207.48 and 90.56 is: 135.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.38 : 207.48 = 90.56 : x
  2. Step 2: Convert to fraction form
    138.38/207.48 = 90.56/x
  3. Step 3: Cross multiply
    138.38x = 207.48 × 90.56
  4. Step 4: Simplify right side
    138.38x = 18,789.39
  5. Step 5: Solve for x
    x = 18,789.39/138.38
  6. Step 6: Final answer
    x = 135.78

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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.