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Finding the Fourth Proportional to 81.26, 122.09 and 76.40

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Solution

The fourth proportional to 81.26, 122.09 and 76.40 is: 114.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.26 : 122.09 = 76.40 : x
  2. Step 2: Convert to fraction form
    81.26/122.09 = 76.40/x
  3. Step 3: Cross multiply
    81.26x = 122.09 × 76.40
  4. Step 4: Simplify right side
    81.26x = 9,326.68
  5. Step 5: Solve for x
    x = 9,326.68/81.26
  6. Step 6: Final answer
    x = 114.78

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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.