Finding the Fourth Proportional to 9,321.72, 12,864.12 and 5,129.92

Step by Step Solution

1. Step 1: Write the proportion equation
   9,321.72 : 12,864.12 = 5,129.92 : x
2. Step 2: Convert to fraction form
   9,321.72/12,864.12 = 5,129.92/x
3. Step 3: Cross multiply
   9,321.72x = 12,864.12 × 5,129.92
4. Step 4: Simplify right side
   9,321.72x = 65,991,906.47
5. Step 5: Solve for x
   x = 65,991,906.47/9,321.72
6. Step 6: Final answer
   x = 7,079.37