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Finding the Third Proportional to 3,990 and 8,680

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Solution

The third proportional to 3,990 and 8,680 is: 18,882.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,990 : 8,680 = 8,680 : x
  2. Step 2: Convert to fraction form
    3,990/8,680 = 8,680/x
  3. Step 3: Cross multiply
    3,990x = 8,680 × 8,680
  4. Step 4: Simplify right side
    3,990x = 75,342,400
  5. Step 5: Solve for x
    x = 75,342,400/3,990
  6. Step 6: Final answer
    x = 18,882.81

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Why These Related Problems?

These problems maintain the same ratio (2.18) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.