Finding the Fourth Proportional to 1,390.93, 1,919.31 and 831.27

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.93 : 1,919.31 = 831.27 : x
2. Step 2: Convert to fraction form
   1,390.93/1,919.31 = 831.27/x
3. Step 3: Cross multiply
   1,390.93x = 1,919.31 × 831.27
4. Step 4: Simplify right side
   1,390.93x = 1,595,455.23
5. Step 5: Solve for x
   x = 1,595,455.23/1,390.93
6. Step 6: Final answer
   x = 1,147.05