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Finding the Fourth Proportional to 31, 42.82 and 20.12

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Solution

The fourth proportional to 31, 42.82 and 20.12 is: 27.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    31 : 42.82 = 20.12 : x
  2. Step 2: Convert to fraction form
    31/42.82 = 20.12/x
  3. Step 3: Cross multiply
    31x = 42.82 × 20.12
  4. Step 4: Simplify right side
    31x = 861.54
  5. Step 5: Solve for x
    x = 861.54/31
  6. Step 6: Final answer
    x = 27.79

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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.