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Finding the Fourth Proportional to 139.76, 209.49 and 81.93

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Solution

The fourth proportional to 139.76, 209.49 and 81.93 is: 122.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.76 : 209.49 = 81.93 : x
  2. Step 2: Convert to fraction form
    139.76/209.49 = 81.93/x
  3. Step 3: Cross multiply
    139.76x = 209.49 × 81.93
  4. Step 4: Simplify right side
    139.76x = 17,163.52
  5. Step 5: Solve for x
    x = 17,163.52/139.76
  6. Step 6: Final answer
    x = 122.81

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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.