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Finding the Fourth Proportional to 69.20, 103.81 and 21.09

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Solution

The fourth proportional to 69.20, 103.81 and 21.09 is: 31.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.20 : 103.81 = 21.09 : x
  2. Step 2: Convert to fraction form
    69.20/103.81 = 21.09/x
  3. Step 3: Cross multiply
    69.20x = 103.81 × 21.09
  4. Step 4: Simplify right side
    69.20x = 2,189.73
  5. Step 5: Solve for x
    x = 2,189.73/69.20
  6. Step 6: Final answer
    x = 31.64

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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.