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Finding the Third Proportional to 12,720 and 19,920

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Solution

The third proportional to 12,720 and 19,920 is: 31,195.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    12,720 : 19,920 = 19,920 : x
  2. Step 2: Convert to fraction form
    12,720/19,920 = 19,920/x
  3. Step 3: Cross multiply
    12,720x = 19,920 × 19,920
  4. Step 4: Simplify right side
    12,720x = 396,806,400
  5. Step 5: Solve for x
    x = 396,806,400/12,720
  6. Step 6: Final answer
    x = 31,195.47

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Why These Related Problems?

These problems maintain the same ratio (1.57) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.