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Finding the Fourth Proportional to 81.38, 122.06 and 20.51

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Solution

The fourth proportional to 81.38, 122.06 and 20.51 is: 30.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.38 : 122.06 = 20.51 : x
  2. Step 2: Convert to fraction form
    81.38/122.06 = 20.51/x
  3. Step 3: Cross multiply
    81.38x = 122.06 × 20.51
  4. Step 4: Simplify right side
    81.38x = 2,503.17
  5. Step 5: Solve for x
    x = 2,503.17/81.38
  6. Step 6: Final answer
    x = 30.76

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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.