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Finding the Fourth Proportional to 81.38, 122.05 and 40.21

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Solution

The fourth proportional to 81.38, 122.05 and 40.21 is: 60.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.38 : 122.05 = 40.21 : x
  2. Step 2: Convert to fraction form
    81.38/122.05 = 40.21/x
  3. Step 3: Cross multiply
    81.38x = 122.05 × 40.21
  4. Step 4: Simplify right side
    81.38x = 4,907.43
  5. Step 5: Solve for x
    x = 4,907.43/81.38
  6. Step 6: Final answer
    x = 60.30

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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.