Finding the Fourth Proportional to 2,128.56, 3,194.16 and 831.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.56 : 3,194.16 = 831.12 : x
2. Step 2: Convert to fraction form
   2,128.56/3,194.16 = 831.12/x
3. Step 3: Cross multiply
   2,128.56x = 3,194.16 × 831.12
4. Step 4: Simplify right side
   2,128.56x = 2,654,730.26
5. Step 5: Solve for x
   x = 2,654,730.26/2,128.56
6. Step 6: Final answer
   x = 1,247.20