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Finding the Third Proportional to 678 and 728

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Solution

The third proportional to 678 and 728 is: 781.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    678 : 728 = 728 : x
  2. Step 2: Convert to fraction form
    678/728 = 728/x
  3. Step 3: Cross multiply
    678x = 728 × 728
  4. Step 4: Simplify right side
    678x = 529,984
  5. Step 5: Solve for x
    x = 529,984/678
  6. Step 6: Final answer
    x = 781.69

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Why These Related Problems?

These problems maintain the same ratio (1.07) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.