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Finding the Fourth Proportional to 819.28, 1,228.80 and 408.40

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Solution

The fourth proportional to 819.28, 1,228.80 and 408.40 is: 612.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.28 : 1,228.80 = 408.40 : x
  2. Step 2: Convert to fraction form
    819.28/1,228.80 = 408.40/x
  3. Step 3: Cross multiply
    819.28x = 1,228.80 × 408.40
  4. Step 4: Simplify right side
    819.28x = 501,841.92
  5. Step 5: Solve for x
    x = 501,841.92/819.28
  6. Step 6: Final answer
    x = 612.54

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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.