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Finding the Fourth Proportional to 721.13, 1,081.82 and 428.49

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Solution

The fourth proportional to 721.13, 1,081.82 and 428.49 is: 642.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.13 : 1,081.82 = 428.49 : x
  2. Step 2: Convert to fraction form
    721.13/1,081.82 = 428.49/x
  3. Step 3: Cross multiply
    721.13x = 1,081.82 × 428.49
  4. Step 4: Simplify right side
    721.13x = 463,550.12
  5. Step 5: Solve for x
    x = 463,550.12/721.13
  6. Step 6: Final answer
    x = 642.82

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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.