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Finding the Third Proportional to 18,420 and 39,720

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Solution

The third proportional to 18,420 and 39,720 is: 85,650.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    18,420 : 39,720 = 39,720 : x
  2. Step 2: Convert to fraction form
    18,420/39,720 = 39,720/x
  3. Step 3: Cross multiply
    18,420x = 39,720 × 39,720
  4. Step 4: Simplify right side
    18,420x = 1,577,678,400
  5. Step 5: Solve for x
    x = 1,577,678,400/18,420
  6. Step 6: Final answer
    x = 85,650.29

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Why These Related Problems?

These problems maintain the same ratio (2.16) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.