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Finding the Third Proportional to 398 and 638.75

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Solution

The third proportional to 398 and 638.75 is: 1,025.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    398 : 638.75 = 638.75 : x
  2. Step 2: Convert to fraction form
    398/638.75 = 638.75/x
  3. Step 3: Cross multiply
    398x = 638.75 × 638.75
  4. Step 4: Simplify right side
    398x = 408,001.56
  5. Step 5: Solve for x
    x = 408,001.56/398
  6. Step 6: Final answer
    x = 1,025.13

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Why These Related Problems?

These problems maintain the same ratio (1.60) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.