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Finding the Third Proportional to 19,990 and 39,980

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Solution

The third proportional to 19,990 and 39,980 is: 79,960

Step by Step Solution

  1. Step 1: Write the proportion equation
    19,990 : 39,980 = 39,980 : x
  2. Step 2: Convert to fraction form
    19,990/39,980 = 39,980/x
  3. Step 3: Cross multiply
    19,990x = 39,980 × 39,980
  4. Step 4: Simplify right side
    19,990x = 1,598,400,400
  5. Step 5: Solve for x
    x = 1,598,400,400/19,990
  6. Step 6: Final answer
    x = 79,960

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Why These Related Problems?

These problems maintain the same ratio (2) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.