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Finding the Fourth Proportional to 138.81, 209.79 and 138.81

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Solution

The fourth proportional to 138.81, 209.79 and 138.81 is: 209.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.81 : 209.79 = 138.81 : x
  2. Step 2: Convert to fraction form
    138.81/209.79 = 138.81/x
  3. Step 3: Cross multiply
    138.81x = 209.79 × 138.81
  4. Step 4: Simplify right side
    138.81x = 29,120.95
  5. Step 5: Solve for x
    x = 29,120.95/138.81
  6. Step 6: Final answer
    x = 209.79

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.