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Finding the Third Proportional to 3,990 and 5,191

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Solution

The third proportional to 3,990 and 5,191 is: 6,753.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,990 : 5,191 = 5,191 : x
  2. Step 2: Convert to fraction form
    3,990/5,191 = 5,191/x
  3. Step 3: Cross multiply
    3,990x = 5,191 × 5,191
  4. Step 4: Simplify right side
    3,990x = 26,946,481
  5. Step 5: Solve for x
    x = 26,946,481/3,990
  6. Step 6: Final answer
    x = 6,753.50

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Why These Related Problems?

These problems maintain the same ratio (1.30) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.