Finding the Fourth Proportional to 2,578.79, 3,558.71 and 1,399.86

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.79 : 3,558.71 = 1,399.86 : x
2. Step 2: Convert to fraction form
   2,578.79/3,558.71 = 1,399.86/x
3. Step 3: Cross multiply
   2,578.79x = 3,558.71 × 1,399.86
4. Step 4: Simplify right side
   2,578.79x = 4,981,699.28
5. Step 5: Solve for x
   x = 4,981,699.28/2,578.79
6. Step 6: Final answer
   x = 1,931.80