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Finding the Fourth Proportional to 138.09, 206.81 and 80.19

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Solution

The fourth proportional to 138.09, 206.81 and 80.19 is: 120.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.09 : 206.81 = 80.19 : x
  2. Step 2: Convert to fraction form
    138.09/206.81 = 80.19/x
  3. Step 3: Cross multiply
    138.09x = 206.81 × 80.19
  4. Step 4: Simplify right side
    138.09x = 16,583.69
  5. Step 5: Solve for x
    x = 16,583.69/138.09
  6. Step 6: Final answer
    x = 120.09

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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.