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Finding the Fourth Proportional to 138.12, 206.96 and 83.85

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Solution

The fourth proportional to 138.12, 206.96 and 83.85 is: 125.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.12 : 206.96 = 83.85 : x
  2. Step 2: Convert to fraction form
    138.12/206.96 = 83.85/x
  3. Step 3: Cross multiply
    138.12x = 206.96 × 83.85
  4. Step 4: Simplify right side
    138.12x = 17,353.18
  5. Step 5: Solve for x
    x = 17,353.18/138.12
  6. Step 6: Final answer
    x = 125.64

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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.