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Finding the Fourth Proportional to 781.43, 1,078.45 and 449.87

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Solution

The fourth proportional to 781.43, 1,078.45 and 449.87 is: 620.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.43 : 1,078.45 = 449.87 : x
  2. Step 2: Convert to fraction form
    781.43/1,078.45 = 449.87/x
  3. Step 3: Cross multiply
    781.43x = 1,078.45 × 449.87
  4. Step 4: Simplify right side
    781.43x = 485,155.78
  5. Step 5: Solve for x
    x = 485,155.78/781.43
  6. Step 6: Final answer
    x = 620.86

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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.