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Finding the Third Proportional to 391 and 638

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Solution

The third proportional to 391 and 638 is: 1,041.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    391 : 638 = 638 : x
  2. Step 2: Convert to fraction form
    391/638 = 638/x
  3. Step 3: Cross multiply
    391x = 638 × 638
  4. Step 4: Simplify right side
    391x = 407,044
  5. Step 5: Solve for x
    x = 407,044/391
  6. Step 6: Final answer
    x = 1,041.03

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Why These Related Problems?

These problems maintain the same ratio (1.63) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.