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Finding the Third Proportional to 3,920 and 8,405

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Solution

The third proportional to 3,920 and 8,405 is: 18,021.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,920 : 8,405 = 8,405 : x
  2. Step 2: Convert to fraction form
    3,920/8,405 = 8,405/x
  3. Step 3: Cross multiply
    3,920x = 8,405 × 8,405
  4. Step 4: Simplify right side
    3,920x = 70,644,025
  5. Step 5: Solve for x
    x = 70,644,025/3,920
  6. Step 6: Final answer
    x = 18,021.43

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Why These Related Problems?

These problems maintain the same ratio (2.14) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.