Finding the Fourth Proportional to 21,111.37, 31,655.34 and 8,640.14

Step by Step Solution

1. Step 1: Write the proportion equation
   21,111.37 : 31,655.34 = 8,640.14 : x
2. Step 2: Convert to fraction form
   21,111.37/31,655.34 = 8,640.14/x
3. Step 3: Cross multiply
   21,111.37x = 31,655.34 × 8,640.14
4. Step 4: Simplify right side
   21,111.37x = 273,506,411.07
5. Step 5: Solve for x
   x = 273,506,411.07/21,111.37
6. Step 6: Final answer
   x = 12,955.41