Finding the Fourth Proportional to 1,391.47, 1,919.31 and 831.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.47 : 1,919.31 = 831.50 : x
2. Step 2: Convert to fraction form
   1,391.47/1,919.31 = 831.50/x
3. Step 3: Cross multiply
   1,391.47x = 1,919.31 × 831.50
4. Step 4: Simplify right side
   1,391.47x = 1,595,906.27
5. Step 5: Solve for x
   x = 1,595,906.27/1,391.47
6. Step 6: Final answer
   x = 1,146.92