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Finding the Fourth Proportional to 819.99, 1,229.99 and 387.45

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Solution

The fourth proportional to 819.99, 1,229.99 and 387.45 is: 581.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.99 : 1,229.99 = 387.45 : x
  2. Step 2: Convert to fraction form
    819.99/1,229.99 = 387.45/x
  3. Step 3: Cross multiply
    819.99x = 1,229.99 × 387.45
  4. Step 4: Simplify right side
    819.99x = 476,557.69
  5. Step 5: Solve for x
    x = 476,557.69/819.99
  6. Step 6: Final answer
    x = 581.18

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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.