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Finding the Fourth Proportional to 80.72, 121.08 and 19.86

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Solution

The fourth proportional to 80.72, 121.08 and 19.86 is: 29.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.72 : 121.08 = 19.86 : x
  2. Step 2: Convert to fraction form
    80.72/121.08 = 19.86/x
  3. Step 3: Cross multiply
    80.72x = 121.08 × 19.86
  4. Step 4: Simplify right side
    80.72x = 2,404.20
  5. Step 5: Solve for x
    x = 2,404.20/80.72
  6. Step 6: Final answer
    x = 29.78

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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.