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Finding the Fourth Proportional to 81.67, 122.54 and 76.84

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Solution

The fourth proportional to 81.67, 122.54 and 76.84 is: 115.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.67 : 122.54 = 76.84 : x
  2. Step 2: Convert to fraction form
    81.67/122.54 = 76.84/x
  3. Step 3: Cross multiply
    81.67x = 122.54 × 76.84
  4. Step 4: Simplify right side
    81.67x = 9,415.97
  5. Step 5: Solve for x
    x = 9,415.97/81.67
  6. Step 6: Final answer
    x = 115.29

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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.