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Finding the Fourth Proportional to 819.60, 1,229.40 and 387.60

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Solution

The fourth proportional to 819.60, 1,229.40 and 387.60 is: 581.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.60 : 1,229.40 = 387.60 : x
  2. Step 2: Convert to fraction form
    819.60/1,229.40 = 387.60/x
  3. Step 3: Cross multiply
    819.60x = 1,229.40 × 387.60
  4. Step 4: Simplify right side
    819.60x = 476,515.44
  5. Step 5: Solve for x
    x = 476,515.44/819.60
  6. Step 6: Final answer
    x = 581.40

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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.