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Finding the Fourth Proportional to 13.92, 20.85 and 12.21

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Solution

The fourth proportional to 13.92, 20.85 and 12.21 is: 18.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.92 : 20.85 = 12.21 : x
  2. Step 2: Convert to fraction form
    13.92/20.85 = 12.21/x
  3. Step 3: Cross multiply
    13.92x = 20.85 × 12.21
  4. Step 4: Simplify right side
    13.92x = 254.58
  5. Step 5: Solve for x
    x = 254.58/13.92
  6. Step 6: Final answer
    x = 18.29

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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.