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Finding the Fourth Proportional to 819.38, 1,229.88 and 638.75

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Solution

The fourth proportional to 819.38, 1,229.88 and 638.75 is: 958.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.38 : 1,229.88 = 638.75 : x
  2. Step 2: Convert to fraction form
    819.38/1,229.88 = 638.75/x
  3. Step 3: Cross multiply
    819.38x = 1,229.88 × 638.75
  4. Step 4: Simplify right side
    819.38x = 785,579.70
  5. Step 5: Solve for x
    x = 785,579.70/819.38
  6. Step 6: Final answer
    x = 958.75

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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.