Finding the Fourth Proportional to 2,578.05, 3,557.70 and 1,399.10

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.05 : 3,557.70 = 1,399.10 : x
2. Step 2: Convert to fraction form
   2,578.05/3,557.70 = 1,399.10/x
3. Step 3: Cross multiply
   2,578.05x = 3,557.70 × 1,399.10
4. Step 4: Simplify right side
   2,578.05x = 4,977,562.18
5. Step 5: Solve for x
   x = 4,977,562.18/2,578.05
6. Step 6: Final answer
   x = 1,930.75