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Finding the Fourth Proportional to 138.78, 207.17 and 120.56

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Solution

The fourth proportional to 138.78, 207.17 and 120.56 is: 179.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 207.17 = 120.56 : x
  2. Step 2: Convert to fraction form
    138.78/207.17 = 120.56/x
  3. Step 3: Cross multiply
    138.78x = 207.17 × 120.56
  4. Step 4: Simplify right side
    138.78x = 24,975.91
  5. Step 5: Solve for x
    x = 24,975.91/138.78
  6. Step 6: Final answer
    x = 179.97

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.