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Finding the Fourth Proportional to 81.30, 121.25 and 80.39

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Solution

The fourth proportional to 81.30, 121.25 and 80.39 is: 119.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.30 : 121.25 = 80.39 : x
  2. Step 2: Convert to fraction form
    81.30/121.25 = 80.39/x
  3. Step 3: Cross multiply
    81.30x = 121.25 × 80.39
  4. Step 4: Simplify right side
    81.30x = 9,747.29
  5. Step 5: Solve for x
    x = 9,747.29/81.30
  6. Step 6: Final answer
    x = 119.89

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.