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Finding the Fourth Proportional to 721.28, 1,081.92 and 396.80

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Solution

The fourth proportional to 721.28, 1,081.92 and 396.80 is: 595.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.28 : 1,081.92 = 396.80 : x
  2. Step 2: Convert to fraction form
    721.28/1,081.92 = 396.80/x
  3. Step 3: Cross multiply
    721.28x = 1,081.92 × 396.80
  4. Step 4: Simplify right side
    721.28x = 429,305.86
  5. Step 5: Solve for x
    x = 429,305.86/721.28
  6. Step 6: Final answer
    x = 595.20

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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.