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Finding the Fourth Proportional to 721.28, 1,081.31 and 355.57

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Solution

The fourth proportional to 721.28, 1,081.31 and 355.57 is: 533.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.28 : 1,081.31 = 355.57 : x
  2. Step 2: Convert to fraction form
    721.28/1,081.31 = 355.57/x
  3. Step 3: Cross multiply
    721.28x = 1,081.31 × 355.57
  4. Step 4: Simplify right side
    721.28x = 384,481.40
  5. Step 5: Solve for x
    x = 384,481.40/721.28
  6. Step 6: Final answer
    x = 533.05

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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.