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Finding the Fourth Proportional to 81.28, 121.90 and 54.37

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Solution

The fourth proportional to 81.28, 121.90 and 54.37 is: 81.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 121.90 = 54.37 : x
  2. Step 2: Convert to fraction form
    81.28/121.90 = 54.37/x
  3. Step 3: Cross multiply
    81.28x = 121.90 × 54.37
  4. Step 4: Simplify right side
    81.28x = 6,627.70
  5. Step 5: Solve for x
    x = 6,627.70/81.28
  6. Step 6: Final answer
    x = 81.54

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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.