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Finding the Third Proportional to 103.78 and 115.65

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Solution

The third proportional to 103.78 and 115.65 is: 128.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.78 : 115.65 = 115.65 : x
  2. Step 2: Convert to fraction form
    103.78/115.65 = 115.65/x
  3. Step 3: Cross multiply
    103.78x = 115.65 × 115.65
  4. Step 4: Simplify right side
    103.78x = 13,374.11
  5. Step 5: Solve for x
    x = 13,374.11/103.78
  6. Step 6: Final answer
    x = 128.87

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Why These Related Problems?

These problems maintain the same ratio (1.11) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.