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Finding the Fourth Proportional to 81.72, 122.69 and 51.19

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Solution

The fourth proportional to 81.72, 122.69 and 51.19 is: 76.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.72 : 122.69 = 51.19 : x
  2. Step 2: Convert to fraction form
    81.72/122.69 = 51.19/x
  3. Step 3: Cross multiply
    81.72x = 122.69 × 51.19
  4. Step 4: Simplify right side
    81.72x = 6,279.94
  5. Step 5: Solve for x
    x = 6,279.94/81.72
  6. Step 6: Final answer
    x = 76.85

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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.