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Finding the Fourth Proportional to 18.78, 28.12 and 12.75

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Solution

The fourth proportional to 18.78, 28.12 and 12.75 is: 19.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.78 : 28.12 = 12.75 : x
  2. Step 2: Convert to fraction form
    18.78/28.12 = 12.75/x
  3. Step 3: Cross multiply
    18.78x = 28.12 × 12.75
  4. Step 4: Simplify right side
    18.78x = 358.33
  5. Step 5: Solve for x
    x = 358.33/18.78
  6. Step 6: Final answer
    x = 19.09

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.