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Finding the Fourth Proportional to 820.20, 1,229.20 and 429.39

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Solution

The fourth proportional to 820.20, 1,229.20 and 429.39 is: 643.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.20 : 1,229.20 = 429.39 : x
  2. Step 2: Convert to fraction form
    820.20/1,229.20 = 429.39/x
  3. Step 3: Cross multiply
    820.20x = 1,229.20 × 429.39
  4. Step 4: Simplify right side
    820.20x = 527,806.19
  5. Step 5: Solve for x
    x = 527,806.19/820.20
  6. Step 6: Final answer
    x = 643.51

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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.