Finding the Fourth Proportional to 2,578.56, 3,558.31 and 1,399.60

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.56 : 3,558.31 = 1,399.60 : x
2. Step 2: Convert to fraction form
   2,578.56/3,558.31 = 1,399.60/x
3. Step 3: Cross multiply
   2,578.56x = 3,558.31 × 1,399.60
4. Step 4: Simplify right side
   2,578.56x = 4,980,210.68
5. Step 5: Solve for x
   x = 4,980,210.68/2,578.56
6. Step 6: Final answer
   x = 1,931.39