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Finding the Fourth Proportional to 81.31, 121.82 and 68.55

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Solution

The fourth proportional to 81.31, 121.82 and 68.55 is: 102.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.31 : 121.82 = 68.55 : x
  2. Step 2: Convert to fraction form
    81.31/121.82 = 68.55/x
  3. Step 3: Cross multiply
    81.31x = 121.82 × 68.55
  4. Step 4: Simplify right side
    81.31x = 8,350.76
  5. Step 5: Solve for x
    x = 8,350.76/81.31
  6. Step 6: Final answer
    x = 102.70

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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.