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Finding the Fourth Proportional to 138.44, 207.90 and 81.56

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Solution

The fourth proportional to 138.44, 207.90 and 81.56 is: 122.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.44 : 207.90 = 81.56 : x
  2. Step 2: Convert to fraction form
    138.44/207.90 = 81.56/x
  3. Step 3: Cross multiply
    138.44x = 207.90 × 81.56
  4. Step 4: Simplify right side
    138.44x = 16,956.32
  5. Step 5: Solve for x
    x = 16,956.32/138.44
  6. Step 6: Final answer
    x = 122.48

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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.