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Finding the Fourth Proportional to 781.39, 1,078.31 and 449.80

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Solution

The fourth proportional to 781.39, 1,078.31 and 449.80 is: 620.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.39 : 1,078.31 = 449.80 : x
  2. Step 2: Convert to fraction form
    781.39/1,078.31 = 449.80/x
  3. Step 3: Cross multiply
    781.39x = 1,078.31 × 449.80
  4. Step 4: Simplify right side
    781.39x = 485,025.80
  5. Step 5: Solve for x
    x = 485,025.80/781.39
  6. Step 6: Final answer
    x = 620.73

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.