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Finding the Fourth Proportional to 820.91, 1,229.36 and 431.24

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Solution

The fourth proportional to 820.91, 1,229.36 and 431.24 is: 645.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.91 : 1,229.36 = 431.24 : x
  2. Step 2: Convert to fraction form
    820.91/1,229.36 = 431.24/x
  3. Step 3: Cross multiply
    820.91x = 1,229.36 × 431.24
  4. Step 4: Simplify right side
    820.91x = 530,147.05
  5. Step 5: Solve for x
    x = 530,147.05/820.91
  6. Step 6: Final answer
    x = 645.80

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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.