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Finding the Fourth Proportional to 781.40, 1,078.37 and 449.88

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Solution

The fourth proportional to 781.40, 1,078.37 and 449.88 is: 620.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.40 : 1,078.37 = 449.88 : x
  2. Step 2: Convert to fraction form
    781.40/1,078.37 = 449.88/x
  3. Step 3: Cross multiply
    781.40x = 1,078.37 × 449.88
  4. Step 4: Simplify right side
    781.40x = 485,132.49
  5. Step 5: Solve for x
    x = 485,132.49/781.40
  6. Step 6: Final answer
    x = 620.85

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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.