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Finding the Fourth Proportional to 138.20, 207.10 and 76.40

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Solution

The fourth proportional to 138.20, 207.10 and 76.40 is: 114.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.20 : 207.10 = 76.40 : x
  2. Step 2: Convert to fraction form
    138.20/207.10 = 76.40/x
  3. Step 3: Cross multiply
    138.20x = 207.10 × 76.40
  4. Step 4: Simplify right side
    138.20x = 15,822.77
  5. Step 5: Solve for x
    x = 15,822.77/138.20
  6. Step 6: Final answer
    x = 114.50

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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.