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Finding the Fourth Proportional to 20.64, 30.91 and 12.09

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Solution

The fourth proportional to 20.64, 30.91 and 12.09 is: 18.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.64 : 30.91 = 12.09 : x
  2. Step 2: Convert to fraction form
    20.64/30.91 = 12.09/x
  3. Step 3: Cross multiply
    20.64x = 30.91 × 12.09
  4. Step 4: Simplify right side
    20.64x = 373.56
  5. Step 5: Solve for x
    x = 373.56/20.64
  6. Step 6: Final answer
    x = 18.10

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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.