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Finding the Fourth Proportional to 81.91, 123.42 and 80.09

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Solution

The fourth proportional to 81.91, 123.42 and 80.09 is: 120.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.91 : 123.42 = 80.09 : x
  2. Step 2: Convert to fraction form
    81.91/123.42 = 80.09/x
  3. Step 3: Cross multiply
    81.91x = 123.42 × 80.09
  4. Step 4: Simplify right side
    81.91x = 9,884.85
  5. Step 5: Solve for x
    x = 9,884.85/81.91
  6. Step 6: Final answer
    x = 120.68

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.