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Finding the Fourth Proportional to 139.87, 209.79 and 82.13

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Solution

The fourth proportional to 139.87, 209.79 and 82.13 is: 123.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.87 : 209.79 = 82.13 : x
  2. Step 2: Convert to fraction form
    139.87/209.79 = 82.13/x
  3. Step 3: Cross multiply
    139.87x = 209.79 × 82.13
  4. Step 4: Simplify right side
    139.87x = 17,229.00
  5. Step 5: Solve for x
    x = 17,229.00/139.87
  6. Step 6: Final answer
    x = 123.18

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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.