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Finding the Fourth Proportional to 81.09, 121.68 and 40.59

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Solution

The fourth proportional to 81.09, 121.68 and 40.59 is: 60.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.09 : 121.68 = 40.59 : x
  2. Step 2: Convert to fraction form
    81.09/121.68 = 40.59/x
  3. Step 3: Cross multiply
    81.09x = 121.68 × 40.59
  4. Step 4: Simplify right side
    81.09x = 4,938.99
  5. Step 5: Solve for x
    x = 4,938.99/81.09
  6. Step 6: Final answer
    x = 60.91

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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.