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Finding the Third Proportional to 640 and 728

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Solution

The third proportional to 640 and 728 is: 828.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    640 : 728 = 728 : x
  2. Step 2: Convert to fraction form
    640/728 = 728/x
  3. Step 3: Cross multiply
    640x = 728 × 728
  4. Step 4: Simplify right side
    640x = 529,984
  5. Step 5: Solve for x
    x = 529,984/640
  6. Step 6: Final answer
    x = 828.10

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Why These Related Problems?

These problems maintain the same ratio (1.14) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.