Finding the Fourth Proportional to 21,109.61, 31,652.71 and 8,638.39

Step by Step Solution

1. Step 1: Write the proportion equation
   21,109.61 : 31,652.71 = 8,638.39 : x
2. Step 2: Convert to fraction form
   21,109.61/31,652.71 = 8,638.39/x
3. Step 3: Cross multiply
   21,109.61x = 31,652.71 × 8,638.39
4. Step 4: Simplify right side
   21,109.61x = 273,428,453.54
5. Step 5: Solve for x
   x = 273,428,453.54/21,109.61
6. Step 6: Final answer
   x = 12,952.80