Finding the Fourth Proportional to 2,231.57, 3,078.81 and 1,391.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,231.57 : 3,078.81 = 1,391.60 : x
2. Step 2: Convert to fraction form
   2,231.57/3,078.81 = 1,391.60/x
3. Step 3: Cross multiply
   2,231.57x = 3,078.81 × 1,391.60
4. Step 4: Simplify right side
   2,231.57x = 4,284,456.60
5. Step 5: Solve for x
   x = 4,284,456.60/2,231.57
6. Step 6: Final answer
   x = 1,919.93