Finding the Fourth Proportional to 1,391.35, 1,919.61 and 831.93

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.35 : 1,919.61 = 831.93 : x
2. Step 2: Convert to fraction form
   1,391.35/1,919.61 = 831.93/x
3. Step 3: Cross multiply
   1,391.35x = 1,919.61 × 831.93
4. Step 4: Simplify right side
   1,391.35x = 1,596,981.15
5. Step 5: Solve for x
   x = 1,596,981.15/1,391.35
6. Step 6: Final answer
   x = 1,147.79