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Finding the Fourth Proportional to 18.78, 28.19 and 11.55

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Solution

The fourth proportional to 18.78, 28.19 and 11.55 is: 17.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.78 : 28.19 = 11.55 : x
  2. Step 2: Convert to fraction form
    18.78/28.19 = 11.55/x
  3. Step 3: Cross multiply
    18.78x = 28.19 × 11.55
  4. Step 4: Simplify right side
    18.78x = 325.54
  5. Step 5: Solve for x
    x = 325.54/18.78
  6. Step 6: Final answer
    x = 17.33

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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.