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Finding the Fourth Proportional to 138.92, 208.20 and 121.88

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Solution

The fourth proportional to 138.92, 208.20 and 121.88 is: 182.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.92 : 208.20 = 121.88 : x
  2. Step 2: Convert to fraction form
    138.92/208.20 = 121.88/x
  3. Step 3: Cross multiply
    138.92x = 208.20 × 121.88
  4. Step 4: Simplify right side
    138.92x = 25,375.42
  5. Step 5: Solve for x
    x = 25,375.42/138.92
  6. Step 6: Final answer
    x = 182.66

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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.