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Finding the Third Proportional to 81 and 123

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Solution

The third proportional to 81 and 123 is: 186.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 123 = 123 : x
  2. Step 2: Convert to fraction form
    81/123 = 123/x
  3. Step 3: Cross multiply
    81x = 123 × 123
  4. Step 4: Simplify right side
    81x = 15,129
  5. Step 5: Solve for x
    x = 15,129/81
  6. Step 6: Final answer
    x = 186.78

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Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.