Finding the Fourth Proportional to 9,321.12, 12,863.04 and 5,129.28

Step by Step Solution

1. Step 1: Write the proportion equation
   9,321.12 : 12,863.04 = 5,129.28 : x
2. Step 2: Convert to fraction form
   9,321.12/12,863.04 = 5,129.28/x
3. Step 3: Cross multiply
   9,321.12x = 12,863.04 × 5,129.28
4. Step 4: Simplify right side
   9,321.12x = 65,978,133.81
5. Step 5: Solve for x
   x = 65,978,133.81/9,321.12
6. Step 6: Final answer
   x = 7,078.35