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Finding the Fourth Proportional to 664.90, 998.43 and 421.90

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Solution

The fourth proportional to 664.90, 998.43 and 421.90 is: 633.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    664.90 : 998.43 = 421.90 : x
  2. Step 2: Convert to fraction form
    664.90/998.43 = 421.90/x
  3. Step 3: Cross multiply
    664.90x = 998.43 × 421.90
  4. Step 4: Simplify right side
    664.90x = 421,237.62
  5. Step 5: Solve for x
    x = 421,237.62/664.90
  6. Step 6: Final answer
    x = 633.54

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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.