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Finding the Fourth Proportional to 81.39, 122.18 and 40.85

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Solution

The fourth proportional to 81.39, 122.18 and 40.85 is: 61.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.39 : 122.18 = 40.85 : x
  2. Step 2: Convert to fraction form
    81.39/122.18 = 40.85/x
  3. Step 3: Cross multiply
    81.39x = 122.18 × 40.85
  4. Step 4: Simplify right side
    81.39x = 4,990.24
  5. Step 5: Solve for x
    x = 4,990.24/81.39
  6. Step 6: Final answer
    x = 61.31

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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.