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Finding the Fourth Proportional to 80.72, 120.96 and 67.92

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Solution

The fourth proportional to 80.72, 120.96 and 67.92 is: 101.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 120.96 = 67.92 : x
  2. Step 2: Convert to fraction form
    80.72/120.96 = 67.92/x
  3. Step 3: Cross multiply
    80.72x = 120.96 × 67.92
  4. Step 4: Simplify right side
    80.72x = 8,215.60
  5. Step 5: Solve for x
    x = 8,215.60/80.72
  6. Step 6: Final answer
    x = 101.78

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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.