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Finding the Third Proportional to 309.56 and 638.81

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Solution

The third proportional to 309.56 and 638.81 is: 1,318.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.56 : 638.81 = 638.81 : x
  2. Step 2: Convert to fraction form
    309.56/638.81 = 638.81/x
  3. Step 3: Cross multiply
    309.56x = 638.81 × 638.81
  4. Step 4: Simplify right side
    309.56x = 408,081.41
  5. Step 5: Solve for x
    x = 408,081.41/309.56
  6. Step 6: Final answer
    x = 1,318.25

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Why These Related Problems?

These problems maintain the same ratio (2.06) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.