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Finding the Third Proportional to 1,920 and 3,987

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Solution

The third proportional to 1,920 and 3,987 is: 8,279.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,920 : 3,987 = 3,987 : x
  2. Step 2: Convert to fraction form
    1,920/3,987 = 3,987/x
  3. Step 3: Cross multiply
    1,920x = 3,987 × 3,987
  4. Step 4: Simplify right side
    1,920x = 15,896,169
  5. Step 5: Solve for x
    x = 15,896,169/1,920
  6. Step 6: Final answer
    x = 8,279.25

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Why These Related Problems?

These problems maintain the same ratio (2.08) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.