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Finding the Third Proportional to 389.75 and 815.38

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Solution

The third proportional to 389.75 and 815.38 is: 1,705.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.75 : 815.38 = 815.38 : x
  2. Step 2: Convert to fraction form
    389.75/815.38 = 815.38/x
  3. Step 3: Cross multiply
    389.75x = 815.38 × 815.38
  4. Step 4: Simplify right side
    389.75x = 664,836.39
  5. Step 5: Solve for x
    x = 664,836.39/389.75
  6. Step 6: Final answer
    x = 1,705.80

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Why These Related Problems?

These problems maintain the same ratio (2.09) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.