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Finding the Fourth Proportional to 665.20, 998.70 and 422.80

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Solution

The fourth proportional to 665.20, 998.70 and 422.80 is: 634.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.20 : 998.70 = 422.80 : x
  2. Step 2: Convert to fraction form
    665.20/998.70 = 422.80/x
  3. Step 3: Cross multiply
    665.20x = 998.70 × 422.80
  4. Step 4: Simplify right side
    665.20x = 422,250.36
  5. Step 5: Solve for x
    x = 422,250.36/665.20
  6. Step 6: Final answer
    x = 634.78

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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.