Finding the Fourth Proportional to 20,612.56, 30,920.04 and 8,131.72

Step by Step Solution

1. Step 1: Write the proportion equation
   20,612.56 : 30,920.04 = 8,131.72 : x
2. Step 2: Convert to fraction form
   20,612.56/30,920.04 = 8,131.72/x
3. Step 3: Cross multiply
   20,612.56x = 30,920.04 × 8,131.72
4. Step 4: Simplify right side
   20,612.56x = 251,433,107.67
5. Step 5: Solve for x
   x = 251,433,107.67/20,612.56
6. Step 6: Final answer
   x = 12,198.05