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Finding the Third Proportional to 308.81 and 643.31

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Solution

The third proportional to 308.81 and 643.31 is: 1,340.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    308.81 : 643.31 = 643.31 : x
  2. Step 2: Convert to fraction form
    308.81/643.31 = 643.31/x
  3. Step 3: Cross multiply
    308.81x = 643.31 × 643.31
  4. Step 4: Simplify right side
    308.81x = 413,850.97
  5. Step 5: Solve for x
    x = 413,850.97/308.81
  6. Step 6: Final answer
    x = 1,340.14

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Why These Related Problems?

These problems maintain the same ratio (2.08) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.