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Finding the Fourth Proportional to 80.42, 120.68 and 39.87

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Solution

The fourth proportional to 80.42, 120.68 and 39.87 is: 59.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.42 : 120.68 = 39.87 : x
  2. Step 2: Convert to fraction form
    80.42/120.68 = 39.87/x
  3. Step 3: Cross multiply
    80.42x = 120.68 × 39.87
  4. Step 4: Simplify right side
    80.42x = 4,811.31
  5. Step 5: Solve for x
    x = 4,811.31/80.42
  6. Step 6: Final answer
    x = 59.83

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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.