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Finding the Fourth Proportional to 819.49, 1,229.78 and 386.68

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Solution

The fourth proportional to 819.49, 1,229.78 and 386.68 is: 580.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.49 : 1,229.78 = 386.68 : x
  2. Step 2: Convert to fraction form
    819.49/1,229.78 = 386.68/x
  3. Step 3: Cross multiply
    819.49x = 1,229.78 × 386.68
  4. Step 4: Simplify right side
    819.49x = 475,531.33
  5. Step 5: Solve for x
    x = 475,531.33/819.49
  6. Step 6: Final answer
    x = 580.28

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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.