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Finding the Fourth Proportional to 13.62, 20.31 and 11.91

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Solution

The fourth proportional to 13.62, 20.31 and 11.91 is: 17.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    13.62 : 20.31 = 11.91 : x
  2. Step 2: Convert to fraction form
    13.62/20.31 = 11.91/x
  3. Step 3: Cross multiply
    13.62x = 20.31 × 11.91
  4. Step 4: Simplify right side
    13.62x = 241.89
  5. Step 5: Solve for x
    x = 241.89/13.62
  6. Step 6: Final answer
    x = 17.76

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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.