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Finding the Fourth Proportional to 80.31, 120.48 and 39.78

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Solution

The fourth proportional to 80.31, 120.48 and 39.78 is: 59.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.31 : 120.48 = 39.78 : x
  2. Step 2: Convert to fraction form
    80.31/120.48 = 39.78/x
  3. Step 3: Cross multiply
    80.31x = 120.48 × 39.78
  4. Step 4: Simplify right side
    80.31x = 4,792.69
  5. Step 5: Solve for x
    x = 4,792.69/80.31
  6. Step 6: Final answer
    x = 59.68

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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.