Finding the Fourth Proportional to 2,578.06, 3,557.70 and 1,399.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.06 : 3,557.70 = 1,399.12 : x
2. Step 2: Convert to fraction form
   2,578.06/3,557.70 = 1,399.12/x
3. Step 3: Cross multiply
   2,578.06x = 3,557.70 × 1,399.12
4. Step 4: Simplify right side
   2,578.06x = 4,977,649.22
5. Step 5: Solve for x
   x = 4,977,649.22/2,578.06
6. Step 6: Final answer
   x = 1,930.77