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Finding the Fourth Proportional to 81.92, 122.34 and 72.81

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Solution

The fourth proportional to 81.92, 122.34 and 72.81 is: 108.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.92 : 122.34 = 72.81 : x
  2. Step 2: Convert to fraction form
    81.92/122.34 = 72.81/x
  3. Step 3: Cross multiply
    81.92x = 122.34 × 72.81
  4. Step 4: Simplify right side
    81.92x = 8,907.58
  5. Step 5: Solve for x
    x = 8,907.58/81.92
  6. Step 6: Final answer
    x = 108.74

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.