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Finding the Fourth Proportional to 721.91, 1,081.37 and 428.51

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Solution

The fourth proportional to 721.91, 1,081.37 and 428.51 is: 641.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.91 : 1,081.37 = 428.51 : x
  2. Step 2: Convert to fraction form
    721.91/1,081.37 = 428.51/x
  3. Step 3: Cross multiply
    721.91x = 1,081.37 × 428.51
  4. Step 4: Simplify right side
    721.91x = 463,370.31
  5. Step 5: Solve for x
    x = 463,370.31/721.91
  6. Step 6: Final answer
    x = 641.87

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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.