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Finding the Fourth Proportional to 81.21, 121.76 and 40.66

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Solution

The fourth proportional to 81.21, 121.76 and 40.66 is: 60.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.21 : 121.76 = 40.66 : x
  2. Step 2: Convert to fraction form
    81.21/121.76 = 40.66/x
  3. Step 3: Cross multiply
    81.21x = 121.76 × 40.66
  4. Step 4: Simplify right side
    81.21x = 4,950.56
  5. Step 5: Solve for x
    x = 4,950.56/81.21
  6. Step 6: Final answer
    x = 60.96

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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.