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Finding the Third Proportional to 396 and 690

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Solution

The third proportional to 396 and 690 is: 1,202.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    396 : 690 = 690 : x
  2. Step 2: Convert to fraction form
    396/690 = 690/x
  3. Step 3: Cross multiply
    396x = 690 × 690
  4. Step 4: Simplify right side
    396x = 476,100
  5. Step 5: Solve for x
    x = 476,100/396
  6. Step 6: Final answer
    x = 1,202.27

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Why These Related Problems?

These problems maintain the same ratio (1.74) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.