Finding the Fourth Proportional to 1,390.54, 1,919.02 and 831.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.54 : 1,919.02 = 831.10 : x
2. Step 2: Convert to fraction form
   1,390.54/1,919.02 = 831.10/x
3. Step 3: Cross multiply
   1,390.54x = 1,919.02 × 831.10
4. Step 4: Simplify right side
   1,390.54x = 1,594,897.52
5. Step 5: Solve for x
   x = 1,594,897.52/1,390.54
6. Step 6: Final answer
   x = 1,146.96