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Finding the Fourth Proportional to 20.38, 30.39 and 18.86

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Solution

The fourth proportional to 20.38, 30.39 and 18.86 is: 28.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.38 : 30.39 = 18.86 : x
  2. Step 2: Convert to fraction form
    20.38/30.39 = 18.86/x
  3. Step 3: Cross multiply
    20.38x = 30.39 × 18.86
  4. Step 4: Simplify right side
    20.38x = 573.16
  5. Step 5: Solve for x
    x = 573.16/20.38
  6. Step 6: Final answer
    x = 28.12

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.