Finding the Fourth Proportional to 1,355.40, 1,869.75 and 831.33

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.40 : 1,869.75 = 831.33 : x
2. Step 2: Convert to fraction form
   1,355.40/1,869.75 = 831.33/x
3. Step 3: Cross multiply
   1,355.40x = 1,869.75 × 831.33
4. Step 4: Simplify right side
   1,355.40x = 1,554,379.27
5. Step 5: Solve for x
   x = 1,554,379.27/1,355.40
6. Step 6: Final answer
   x = 1,146.80