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Finding the Fourth Proportional to 81.91, 122.92 and 47.72

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Solution

The fourth proportional to 81.91, 122.92 and 47.72 is: 71.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.91 : 122.92 = 47.72 : x
  2. Step 2: Convert to fraction form
    81.91/122.92 = 47.72/x
  3. Step 3: Cross multiply
    81.91x = 122.92 × 47.72
  4. Step 4: Simplify right side
    81.91x = 5,865.93
  5. Step 5: Solve for x
    x = 5,865.93/81.91
  6. Step 6: Final answer
    x = 71.61

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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.