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Finding the Third Proportional to 6,405 and 9,990

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Solution

The third proportional to 6,405 and 9,990 is: 15,581.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    6,405 : 9,990 = 9,990 : x
  2. Step 2: Convert to fraction form
    6,405/9,990 = 9,990/x
  3. Step 3: Cross multiply
    6,405x = 9,990 × 9,990
  4. Step 4: Simplify right side
    6,405x = 99,800,100
  5. Step 5: Solve for x
    x = 99,800,100/6,405
  6. Step 6: Final answer
    x = 15,581.59

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Why These Related Problems?

These problems maintain the same ratio (1.56) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.