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Finding the Third Proportional to 81,720 and 128,412

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Solution

The third proportional to 81,720 and 128,412 is: 201,782.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    81,720 : 128,412 = 128,412 : x
  2. Step 2: Convert to fraction form
    81,720/128,412 = 128,412/x
  3. Step 3: Cross multiply
    81,720x = 128,412 × 128,412
  4. Step 4: Simplify right side
    81,720x = 16,489,641,744
  5. Step 5: Solve for x
    x = 16,489,641,744/81,720
  6. Step 6: Final answer
    x = 201,782.20

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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.