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Finding the Third Proportional to 391.50 and 831

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Solution

The third proportional to 391.50 and 831 is: 1,763.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.50 : 831 = 831 : x
  2. Step 2: Convert to fraction form
    391.50/831 = 831/x
  3. Step 3: Cross multiply
    391.50x = 831 × 831
  4. Step 4: Simplify right side
    391.50x = 690,561
  5. Step 5: Solve for x
    x = 690,561/391.50
  6. Step 6: Final answer
    x = 1,763.89

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Why These Related Problems?

These problems maintain the same ratio (2.12) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.