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Finding the Third Proportional to 339.75 and 688.78

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Solution

The third proportional to 339.75 and 688.78 is: 1,396.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    339.75 : 688.78 = 688.78 : x
  2. Step 2: Convert to fraction form
    339.75/688.78 = 688.78/x
  3. Step 3: Cross multiply
    339.75x = 688.78 × 688.78
  4. Step 4: Simplify right side
    339.75x = 474,419.61
  5. Step 5: Solve for x
    x = 474,419.61/339.75
  6. Step 6: Final answer
    x = 1,396.38

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Why These Related Problems?

These problems maintain the same ratio (2.03) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.