Finding the Fourth Proportional to 8,128.78, 12,120.32 and 7,981.16

Step by Step Solution

1. Step 1: Write the proportion equation
   8,128.78 : 12,120.32 = 7,981.16 : x
2. Step 2: Convert to fraction form
   8,128.78/12,120.32 = 7,981.16/x
3. Step 3: Cross multiply
   8,128.78x = 12,120.32 × 7,981.16
4. Step 4: Simplify right side
   8,128.78x = 96,734,172.52
5. Step 5: Solve for x
   x = 96,734,172.52/8,128.78
6. Step 6: Final answer
   x = 11,900.21