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Finding the Fourth Proportional to 665.20, 996.60 and 408.40

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Solution

The fourth proportional to 665.20, 996.60 and 408.40 is: 611.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.20 : 996.60 = 408.40 : x
  2. Step 2: Convert to fraction form
    665.20/996.60 = 408.40/x
  3. Step 3: Cross multiply
    665.20x = 996.60 × 408.40
  4. Step 4: Simplify right side
    665.20x = 407,011.44
  5. Step 5: Solve for x
    x = 407,011.44/665.20
  6. Step 6: Final answer
    x = 611.86

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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.