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Finding the Third Proportional to 120.38 and 128.75

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Solution

The third proportional to 120.38 and 128.75 is: 137.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.38 : 128.75 = 128.75 : x
  2. Step 2: Convert to fraction form
    120.38/128.75 = 128.75/x
  3. Step 3: Cross multiply
    120.38x = 128.75 × 128.75
  4. Step 4: Simplify right side
    120.38x = 16,576.56
  5. Step 5: Solve for x
    x = 16,576.56/120.38
  6. Step 6: Final answer
    x = 137.71

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Why These Related Problems?

These problems maintain the same ratio (1.07) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.