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Finding the Fourth Proportional to 81.57, 122.39 and 79.82

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Solution

The fourth proportional to 81.57, 122.39 and 79.82 is: 119.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.57 : 122.39 = 79.82 : x
  2. Step 2: Convert to fraction form
    81.57/122.39 = 79.82/x
  3. Step 3: Cross multiply
    81.57x = 122.39 × 79.82
  4. Step 4: Simplify right side
    81.57x = 9,769.17
  5. Step 5: Solve for x
    x = 9,769.17/81.57
  6. Step 6: Final answer
    x = 119.76

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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.