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Finding the Third Proportional to 643.99 and 999.21

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Solution

The third proportional to 643.99 and 999.21 is: 1,550.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.99 : 999.21 = 999.21 : x
  2. Step 2: Convert to fraction form
    643.99/999.21 = 999.21/x
  3. Step 3: Cross multiply
    643.99x = 999.21 × 999.21
  4. Step 4: Simplify right side
    643.99x = 998,422.50
  5. Step 5: Solve for x
    x = 998,422.50/643.99
  6. Step 6: Final answer
    x = 1,550.36

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Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.