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Finding the Fourth Proportional to 820.12, 1,229.20 and 408.32

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Solution

The fourth proportional to 820.12, 1,229.20 and 408.32 is: 611.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.12 : 1,229.20 = 408.32 : x
  2. Step 2: Convert to fraction form
    820.12/1,229.20 = 408.32/x
  3. Step 3: Cross multiply
    820.12x = 1,229.20 × 408.32
  4. Step 4: Simplify right side
    820.12x = 501,906.94
  5. Step 5: Solve for x
    x = 501,906.94/820.12
  6. Step 6: Final answer
    x = 611.99

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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.