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Finding the Fourth Proportional to 641.20, 961.61 and 421.82

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Solution

The fourth proportional to 641.20, 961.61 and 421.82 is: 632.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.20 : 961.61 = 421.82 : x
  2. Step 2: Convert to fraction form
    641.20/961.61 = 421.82/x
  3. Step 3: Cross multiply
    641.20x = 961.61 × 421.82
  4. Step 4: Simplify right side
    641.20x = 405,626.33
  5. Step 5: Solve for x
    x = 405,626.33/641.20
  6. Step 6: Final answer
    x = 632.61

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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.