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Finding the Fourth Proportional to 81.28, 121.96 and 38.48

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Solution

The fourth proportional to 81.28, 121.96 and 38.48 is: 57.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 121.96 = 38.48 : x
  2. Step 2: Convert to fraction form
    81.28/121.96 = 38.48/x
  3. Step 3: Cross multiply
    81.28x = 121.96 × 38.48
  4. Step 4: Simplify right side
    81.28x = 4,693.02
  5. Step 5: Solve for x
    x = 4,693.02/81.28
  6. Step 6: Final answer
    x = 57.74

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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.