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Finding the Fourth Proportional to 81.28, 121.78 and 40.60

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Solution

The fourth proportional to 81.28, 121.78 and 40.60 is: 60.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.28 : 121.78 = 40.60 : x
  2. Step 2: Convert to fraction form
    81.28/121.78 = 40.60/x
  3. Step 3: Cross multiply
    81.28x = 121.78 × 40.60
  4. Step 4: Simplify right side
    81.28x = 4,944.27
  5. Step 5: Solve for x
    x = 4,944.27/81.28
  6. Step 6: Final answer
    x = 60.83

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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.