Finding the Fourth Proportional to 2,578.28, 3,557.99 and 1,399.34

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.28 : 3,557.99 = 1,399.34 : x
2. Step 2: Convert to fraction form
   2,578.28/3,557.99 = 1,399.34/x
3. Step 3: Cross multiply
   2,578.28x = 3,557.99 × 1,399.34
4. Step 4: Simplify right side
   2,578.28x = 4,978,812.94
5. Step 5: Solve for x
   x = 4,978,812.94/2,578.28
6. Step 6: Final answer
   x = 1,931.06