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Finding the Fourth Proportional to 138.20, 207.12 and 77.25

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Solution

The fourth proportional to 138.20, 207.12 and 77.25 is: 115.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 207.12 = 77.25 : x
  2. Step 2: Convert to fraction form
    138.20/207.12 = 77.25/x
  3. Step 3: Cross multiply
    138.20x = 207.12 × 77.25
  4. Step 4: Simplify right side
    138.20x = 16,000.02
  5. Step 5: Solve for x
    x = 16,000.02/138.20
  6. Step 6: Final answer
    x = 115.77

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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.