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Finding the Fourth Proportional to 20.82, 31.22 and 13.20

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Solution

The fourth proportional to 20.82, 31.22 and 13.20 is: 19.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.82 : 31.22 = 13.20 : x
  2. Step 2: Convert to fraction form
    20.82/31.22 = 13.20/x
  3. Step 3: Cross multiply
    20.82x = 31.22 × 13.20
  4. Step 4: Simplify right side
    20.82x = 412.10
  5. Step 5: Solve for x
    x = 412.10/20.82
  6. Step 6: Final answer
    x = 19.79

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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.