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Finding the Fourth Proportional to 20.51, 28.31 and 12.21

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Solution

The fourth proportional to 20.51, 28.31 and 12.21 is: 16.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.51 : 28.31 = 12.21 : x
  2. Step 2: Convert to fraction form
    20.51/28.31 = 12.21/x
  3. Step 3: Cross multiply
    20.51x = 28.31 × 12.21
  4. Step 4: Simplify right side
    20.51x = 345.60
  5. Step 5: Solve for x
    x = 345.60/20.51
  6. Step 6: Final answer
    x = 16.85

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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.