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Finding the Fourth Proportional to 426.20, 639.67 and 220.91

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Solution

The fourth proportional to 426.20, 639.67 and 220.91 is: 331.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.20 : 639.67 = 220.91 : x
  2. Step 2: Convert to fraction form
    426.20/639.67 = 220.91/x
  3. Step 3: Cross multiply
    426.20x = 639.67 × 220.91
  4. Step 4: Simplify right side
    426.20x = 141,306.58
  5. Step 5: Solve for x
    x = 141,306.58/426.20
  6. Step 6: Final answer
    x = 331.55

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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.