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Finding the Fourth Proportional to 81.85, 122.76 and 20.97

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Solution

The fourth proportional to 81.85, 122.76 and 20.97 is: 31.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.85 : 122.76 = 20.97 : x
  2. Step 2: Convert to fraction form
    81.85/122.76 = 20.97/x
  3. Step 3: Cross multiply
    81.85x = 122.76 × 20.97
  4. Step 4: Simplify right side
    81.85x = 2,574.17
  5. Step 5: Solve for x
    x = 2,574.17/81.85
  6. Step 6: Final answer
    x = 31.45

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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.