Finding the Fourth Proportional to 2,578.11, 3,557.81 and 1,399.18

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.11 : 3,557.81 = 1,399.18 : x
2. Step 2: Convert to fraction form
   2,578.11/3,557.81 = 1,399.18/x
3. Step 3: Cross multiply
   2,578.11x = 3,557.81 × 1,399.18
4. Step 4: Simplify right side
   2,578.11x = 4,978,016.60
5. Step 5: Solve for x
   x = 4,978,016.60/2,578.11
6. Step 6: Final answer
   x = 1,930.88