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Finding the Fourth Proportional to 819.21, 1,229.12 and 408.34

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Solution

The fourth proportional to 819.21, 1,229.12 and 408.34 is: 612.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.21 : 1,229.12 = 408.34 : x
  2. Step 2: Convert to fraction form
    819.21/1,229.12 = 408.34/x
  3. Step 3: Cross multiply
    819.21x = 1,229.12 × 408.34
  4. Step 4: Simplify right side
    819.21x = 501,902.18
  5. Step 5: Solve for x
    x = 501,902.18/819.21
  6. Step 6: Final answer
    x = 612.66

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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.