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Finding the Fourth Proportional to 81.97, 122.79 and 38.57

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Solution

The fourth proportional to 81.97, 122.79 and 38.57 is: 57.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.97 : 122.79 = 38.57 : x
  2. Step 2: Convert to fraction form
    81.97/122.79 = 38.57/x
  3. Step 3: Cross multiply
    81.97x = 122.79 × 38.57
  4. Step 4: Simplify right side
    81.97x = 4,736.12
  5. Step 5: Solve for x
    x = 4,736.12/81.97
  6. Step 6: Final answer
    x = 57.78

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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.