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Finding the Fourth Proportional to 81.50, 122.26 and 81.21

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Solution

The fourth proportional to 81.50, 122.26 and 81.21 is: 121.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.50 : 122.26 = 81.21 : x
  2. Step 2: Convert to fraction form
    81.50/122.26 = 81.21/x
  3. Step 3: Cross multiply
    81.50x = 122.26 × 81.21
  4. Step 4: Simplify right side
    81.50x = 9,928.73
  5. Step 5: Solve for x
    x = 9,928.73/81.50
  6. Step 6: Final answer
    x = 121.82

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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.