Finding the Fourth Proportional to 2,578.78, 3,558.66 and 1,399.84

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.78 : 3,558.66 = 1,399.84 : x
2. Step 2: Convert to fraction form
   2,578.78/3,558.66 = 1,399.84/x
3. Step 3: Cross multiply
   2,578.78x = 3,558.66 × 1,399.84
4. Step 4: Simplify right side
   2,578.78x = 4,981,554.61
5. Step 5: Solve for x
   x = 4,981,554.61/2,578.78
6. Step 6: Final answer
   x = 1,931.75