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Finding the Fourth Proportional to 81.87, 122.85 and 38.58

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Solution

The fourth proportional to 81.87, 122.85 and 38.58 is: 57.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.87 : 122.85 = 38.58 : x
  2. Step 2: Convert to fraction form
    81.87/122.85 = 38.58/x
  3. Step 3: Cross multiply
    81.87x = 122.85 × 38.58
  4. Step 4: Simplify right side
    81.87x = 4,739.55
  5. Step 5: Solve for x
    x = 4,739.55/81.87
  6. Step 6: Final answer
    x = 57.89

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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.