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Finding the Fourth Proportional to 81.90, 123.39 and 80.96

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Solution

The fourth proportional to 81.90, 123.39 and 80.96 is: 121.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.90 : 123.39 = 80.96 : x
  2. Step 2: Convert to fraction form
    81.90/123.39 = 80.96/x
  3. Step 3: Cross multiply
    81.90x = 123.39 × 80.96
  4. Step 4: Simplify right side
    81.90x = 9,989.04
  5. Step 5: Solve for x
    x = 9,989.04/81.90
  6. Step 6: Final answer
    x = 121.97

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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.