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Finding the Third Proportional to 521 and 638

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Solution

The third proportional to 521 and 638 is: 781.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    521 : 638 = 638 : x
  2. Step 2: Convert to fraction form
    521/638 = 638/x
  3. Step 3: Cross multiply
    521x = 638 × 638
  4. Step 4: Simplify right side
    521x = 407,044
  5. Step 5: Solve for x
    x = 407,044/521
  6. Step 6: Final answer
    x = 781.27

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Why These Related Problems?

These problems maintain the same ratio (1.22) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.