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Finding the Fourth Proportional to 819.80, 1,230.30 and 638.75

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Solution

The fourth proportional to 819.80, 1,230.30 and 638.75 is: 958.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    819.80 : 1,230.30 = 638.75 : x
  2. Step 2: Convert to fraction form
    819.80/1,230.30 = 638.75/x
  3. Step 3: Cross multiply
    819.80x = 1,230.30 × 638.75
  4. Step 4: Simplify right side
    819.80x = 785,854.13
  5. Step 5: Solve for x
    x = 785,854.13/819.80
  6. Step 6: Final answer
    x = 958.59

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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.