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Finding the Third Proportional to 820 and 2,155

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Solution

The third proportional to 820 and 2,155 is: 5,663.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    820 : 2,155 = 2,155 : x
  2. Step 2: Convert to fraction form
    820/2,155 = 2,155/x
  3. Step 3: Cross multiply
    820x = 2,155 × 2,155
  4. Step 4: Simplify right side
    820x = 4,644,025
  5. Step 5: Solve for x
    x = 4,644,025/820
  6. Step 6: Final answer
    x = 5,663.45

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Why These Related Problems?

These problems maintain the same ratio (2.63) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.