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Finding the Fourth Proportional to 139.29, 208.71 and 81.54

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Solution

The fourth proportional to 139.29, 208.71 and 81.54 is: 122.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.29 : 208.71 = 81.54 : x
  2. Step 2: Convert to fraction form
    139.29/208.71 = 81.54/x
  3. Step 3: Cross multiply
    139.29x = 208.71 × 81.54
  4. Step 4: Simplify right side
    139.29x = 17,018.21
  5. Step 5: Solve for x
    x = 17,018.21/139.29
  6. Step 6: Final answer
    x = 122.18

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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.