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Finding the Third Proportional to 640 and 820

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Solution

The third proportional to 640 and 820 is: 1,050.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    640 : 820 = 820 : x
  2. Step 2: Convert to fraction form
    640/820 = 820/x
  3. Step 3: Cross multiply
    640x = 820 × 820
  4. Step 4: Simplify right side
    640x = 672,400
  5. Step 5: Solve for x
    x = 672,400/640
  6. Step 6: Final answer
    x = 1,050.63

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Why These Related Problems?

These problems maintain the same ratio (1.28) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.