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Finding the Third Proportional to 138.69 and 199.78

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Solution

The third proportional to 138.69 and 199.78 is: 287.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.69 : 199.78 = 199.78 : x
  2. Step 2: Convert to fraction form
    138.69/199.78 = 199.78/x
  3. Step 3: Cross multiply
    138.69x = 199.78 × 199.78
  4. Step 4: Simplify right side
    138.69x = 39,912.55
  5. Step 5: Solve for x
    x = 39,912.55/138.69
  6. Step 6: Final answer
    x = 287.79

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Why These Related Problems?

These problems maintain the same ratio (1.44) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.