Finding the Fourth Proportional to 12,111.36, 18,128.16 and 8,155.32

Step by Step Solution

1. Step 1: Write the proportion equation
   12,111.36 : 18,128.16 = 8,155.32 : x
2. Step 2: Convert to fraction form
   12,111.36/18,128.16 = 8,155.32/x
3. Step 3: Cross multiply
   12,111.36x = 18,128.16 × 8,155.32
4. Step 4: Simplify right side
   12,111.36x = 147,840,945.81
5. Step 5: Solve for x
   x = 147,840,945.81/12,111.36
6. Step 6: Final answer
   x = 12,206.80