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Finding the Fourth Proportional to 138.30, 207.28 and 80.61

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Solution

The fourth proportional to 138.30, 207.28 and 80.61 is: 120.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.30 : 207.28 = 80.61 : x
  2. Step 2: Convert to fraction form
    138.30/207.28 = 80.61/x
  3. Step 3: Cross multiply
    138.30x = 207.28 × 80.61
  4. Step 4: Simplify right side
    138.30x = 16,708.84
  5. Step 5: Solve for x
    x = 16,708.84/138.30
  6. Step 6: Final answer
    x = 120.82

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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.