Finding the Fourth Proportional to 21,007.30, 31,446.15 and 12,216.10

Step by Step Solution

1. Step 1: Write the proportion equation
   21,007.30 : 31,446.15 = 12,216.10 : x
2. Step 2: Convert to fraction form
   21,007.30/31,446.15 = 12,216.10/x
3. Step 3: Cross multiply
   21,007.30x = 31,446.15 × 12,216.10
4. Step 4: Simplify right side
   21,007.30x = 384,149,313.02
5. Step 5: Solve for x
   x = 384,149,313.02/21,007.30
6. Step 6: Final answer
   x = 18,286.47