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Finding the Third Proportional to 3,900 and 8,400

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Solution

The third proportional to 3,900 and 8,400 is: 18,092.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,900 : 8,400 = 8,400 : x
  2. Step 2: Convert to fraction form
    3,900/8,400 = 8,400/x
  3. Step 3: Cross multiply
    3,900x = 8,400 × 8,400
  4. Step 4: Simplify right side
    3,900x = 70,560,000
  5. Step 5: Solve for x
    x = 70,560,000/3,900
  6. Step 6: Final answer
    x = 18,092.31

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Why These Related Problems?

These problems maintain the same ratio (2.15) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.