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Finding the Third Proportional to 418.92 and 643.78

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Solution

The third proportional to 418.92 and 643.78 is: 989.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    418.92 : 643.78 = 643.78 : x
  2. Step 2: Convert to fraction form
    418.92/643.78 = 643.78/x
  3. Step 3: Cross multiply
    418.92x = 643.78 × 643.78
  4. Step 4: Simplify right side
    418.92x = 414,454.30
  5. Step 5: Solve for x
    x = 414,454.30/418.92
  6. Step 6: Final answer
    x = 989.34

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Why These Related Problems?

These problems maintain the same ratio (1.54) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.