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Finding the Third Proportional to 1,920 and 3,900

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Solution

The third proportional to 1,920 and 3,900 is: 7,921.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,920 : 3,900 = 3,900 : x
  2. Step 2: Convert to fraction form
    1,920/3,900 = 3,900/x
  3. Step 3: Cross multiply
    1,920x = 3,900 × 3,900
  4. Step 4: Simplify right side
    1,920x = 15,210,000
  5. Step 5: Solve for x
    x = 15,210,000/1,920
  6. Step 6: Final answer
    x = 7,921.88

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Why These Related Problems?

These problems maintain the same ratio (2.03) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.