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Finding the Fourth Proportional to 819.87, 1,230.21 and 408.99

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Solution

The fourth proportional to 819.87, 1,230.21 and 408.99 is: 613.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.87 : 1,230.21 = 408.99 : x
  2. Step 2: Convert to fraction form
    819.87/1,230.21 = 408.99/x
  3. Step 3: Cross multiply
    819.87x = 1,230.21 × 408.99
  4. Step 4: Simplify right side
    819.87x = 503,143.59
  5. Step 5: Solve for x
    x = 503,143.59/819.87
  6. Step 6: Final answer
    x = 613.69

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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.