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Finding the Fourth Proportional to 20.88, 28.81 and 13.11

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Solution

The fourth proportional to 20.88, 28.81 and 13.11 is: 18.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.88 : 28.81 = 13.11 : x
  2. Step 2: Convert to fraction form
    20.88/28.81 = 13.11/x
  3. Step 3: Cross multiply
    20.88x = 28.81 × 13.11
  4. Step 4: Simplify right side
    20.88x = 377.67
  5. Step 5: Solve for x
    x = 377.67/20.88
  6. Step 6: Final answer
    x = 18.09

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.