Finding the Fourth Proportional to 1,391.46, 1,920.09 and 831.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.46 : 1,920.09 = 831.82 : x
2. Step 2: Convert to fraction form
   1,391.46/1,920.09 = 831.82/x
3. Step 3: Cross multiply
   1,391.46x = 1,920.09 × 831.82
4. Step 4: Simplify right side
   1,391.46x = 1,597,165.10
5. Step 5: Solve for x
   x = 1,597,165.10/1,391.46
6. Step 6: Final answer
   x = 1,147.83