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Finding the Fourth Proportional to 781.38, 1,078.38 and 449.91

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Solution

The fourth proportional to 781.38, 1,078.38 and 449.91 is: 620.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.38 : 1,078.38 = 449.91 : x
  2. Step 2: Convert to fraction form
    781.38/1,078.38 = 449.91/x
  3. Step 3: Cross multiply
    781.38x = 1,078.38 × 449.91
  4. Step 4: Simplify right side
    781.38x = 485,173.95
  5. Step 5: Solve for x
    x = 485,173.95/781.38
  6. Step 6: Final answer
    x = 620.92

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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.