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Finding the Fourth Proportional to 81.92, 122.55 and 61.31

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Solution

The fourth proportional to 81.92, 122.55 and 61.31 is: 91.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.92 : 122.55 = 61.31 : x
  2. Step 2: Convert to fraction form
    81.92/122.55 = 61.31/x
  3. Step 3: Cross multiply
    81.92x = 122.55 × 61.31
  4. Step 4: Simplify right side
    81.92x = 7,512.93
  5. Step 5: Solve for x
    x = 7,512.93/81.92
  6. Step 6: Final answer
    x = 91.72

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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.