Finding the Fourth Proportional to 21,107.61, 31,649.72 and 8,636.39

Step by Step Solution

1. Step 1: Write the proportion equation
   21,107.61 : 31,649.72 = 8,636.39 : x
2. Step 2: Convert to fraction form
   21,107.61/31,649.72 = 8,636.39/x
3. Step 3: Cross multiply
   21,107.61x = 31,649.72 × 8,636.39
4. Step 4: Simplify right side
   21,107.61x = 273,339,123.88
5. Step 5: Solve for x
   x = 273,339,123.88/21,107.61
6. Step 6: Final answer
   x = 12,949.79