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Finding the Fourth Proportional to 21.11, 31.82 and 20.12

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Solution

The fourth proportional to 21.11, 31.82 and 20.12 is: 30.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.11 : 31.82 = 20.12 : x
  2. Step 2: Convert to fraction form
    21.11/31.82 = 20.12/x
  3. Step 3: Cross multiply
    21.11x = 31.82 × 20.12
  4. Step 4: Simplify right side
    21.11x = 639.96
  5. Step 5: Solve for x
    x = 639.96/21.11
  6. Step 6: Final answer
    x = 30.32

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.