Finding the Fourth Proportional to 2,578.72, 3,558.66 and 1,399.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.72 : 3,558.66 = 1,399.81 : x
2. Step 2: Convert to fraction form
   2,578.72/3,558.66 = 1,399.81/x
3. Step 3: Cross multiply
   2,578.72x = 3,558.66 × 1,399.81
4. Step 4: Simplify right side
   2,578.72x = 4,981,447.85
5. Step 5: Solve for x
   x = 4,981,447.85/2,578.72
6. Step 6: Final answer
   x = 1,931.75