Finding the Fourth Proportional to 12,606.80, 17,391.38 and 8,128.31

Step by Step Solution

1. Step 1: Write the proportion equation
   12,606.80 : 17,391.38 = 8,128.31 : x
2. Step 2: Convert to fraction form
   12,606.80/17,391.38 = 8,128.31/x
3. Step 3: Cross multiply
   12,606.80x = 17,391.38 × 8,128.31
4. Step 4: Simplify right side
   12,606.80x = 141,362,400.37
5. Step 5: Solve for x
   x = 141,362,400.37/12,606.80
6. Step 6: Final answer
   x = 11,213.19