Finding the Fourth Proportional to 1,391.02, 1,919.78 and 831.49

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.02 : 1,919.78 = 831.49 : x
2. Step 2: Convert to fraction form
   1,391.02/1,919.78 = 831.49/x
3. Step 3: Cross multiply
   1,391.02x = 1,919.78 × 831.49
4. Step 4: Simplify right side
   1,391.02x = 1,596,273.07
5. Step 5: Solve for x
   x = 1,596,273.07/1,391.02
6. Step 6: Final answer
   x = 1,147.55