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Finding the Fourth Proportional to 721.78, 1,081.91 and 515.74

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Solution

The fourth proportional to 721.78, 1,081.91 and 515.74 is: 773.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.78 : 1,081.91 = 515.74 : x
  2. Step 2: Convert to fraction form
    721.78/1,081.91 = 515.74/x
  3. Step 3: Cross multiply
    721.78x = 1,081.91 × 515.74
  4. Step 4: Simplify right side
    721.78x = 557,982.85
  5. Step 5: Solve for x
    x = 557,982.85/721.78
  6. Step 6: Final answer
    x = 773.06

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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.