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Finding the Fourth Proportional to 81.20, 121.68 and 55.54

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Solution

The fourth proportional to 81.20, 121.68 and 55.54 is: 83.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.20 : 121.68 = 55.54 : x
  2. Step 2: Convert to fraction form
    81.20/121.68 = 55.54/x
  3. Step 3: Cross multiply
    81.20x = 121.68 × 55.54
  4. Step 4: Simplify right side
    81.20x = 6,757.42
  5. Step 5: Solve for x
    x = 6,757.42/81.20
  6. Step 6: Final answer
    x = 83.22

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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.