Finding the Fourth Proportional to 21,222.82, 31,790.46 and 12,431.08

Step by Step Solution

1. Step 1: Write the proportion equation
   21,222.82 : 31,790.46 = 12,431.08 : x
2. Step 2: Convert to fraction form
   21,222.82/31,790.46 = 12,431.08/x
3. Step 3: Cross multiply
   21,222.82x = 31,790.46 × 12,431.08
4. Step 4: Simplify right side
   21,222.82x = 395,189,751.50
5. Step 5: Solve for x
   x = 395,189,751.50/21,222.82
6. Step 6: Final answer
   x = 18,620.98