Finding the Fourth Proportional to 13,821.72, 20,729.52 and 3,960.96

Step by Step Solution

1. Step 1: Write the proportion equation
   13,821.72 : 20,729.52 = 3,960.96 : x
2. Step 2: Convert to fraction form
   13,821.72/20,729.52 = 3,960.96/x
3. Step 3: Cross multiply
   13,821.72x = 20,729.52 × 3,960.96
4. Step 4: Simplify right side
   13,821.72x = 82,108,799.54
5. Step 5: Solve for x
   x = 82,108,799.54/13,821.72
6. Step 6: Final answer
   x = 5,940.56