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Finding the Fourth Proportional to 81.79, 123.17 and 76.39

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Solution

The fourth proportional to 81.79, 123.17 and 76.39 is: 115.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.79 : 123.17 = 76.39 : x
  2. Step 2: Convert to fraction form
    81.79/123.17 = 76.39/x
  3. Step 3: Cross multiply
    81.79x = 123.17 × 76.39
  4. Step 4: Simplify right side
    81.79x = 9,408.96
  5. Step 5: Solve for x
    x = 9,408.96/81.79
  6. Step 6: Final answer
    x = 115.04

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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.