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Finding the Fourth Proportional to 139.70, 209.35 and 81.82

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Solution

The fourth proportional to 139.70, 209.35 and 81.82 is: 122.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.70 : 209.35 = 81.82 : x
  2. Step 2: Convert to fraction form
    139.70/209.35 = 81.82/x
  3. Step 3: Cross multiply
    139.70x = 209.35 × 81.82
  4. Step 4: Simplify right side
    139.70x = 17,129.38
  5. Step 5: Solve for x
    x = 17,129.38/139.70
  6. Step 6: Final answer
    x = 122.61

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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.