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Finding the Fourth Proportional to 721.45, 1,081.40 and 515.39

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Solution

The fourth proportional to 721.45, 1,081.40 and 515.39 is: 772.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.45 : 1,081.40 = 515.39 : x
  2. Step 2: Convert to fraction form
    721.45/1,081.40 = 515.39/x
  3. Step 3: Cross multiply
    721.45x = 1,081.40 × 515.39
  4. Step 4: Simplify right side
    721.45x = 557,342.75
  5. Step 5: Solve for x
    x = 557,342.75/721.45
  6. Step 6: Final answer
    x = 772.53

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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.