Finding the Fourth Proportional to 2,578.69, 3,558.66 and 1,399.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,578.69 : 3,558.66 = 1,399.76 : x
2. Step 2: Convert to fraction form
   2,578.69/3,558.66 = 1,399.76/x
3. Step 3: Cross multiply
   2,578.69x = 3,558.66 × 1,399.76
4. Step 4: Simplify right side
   2,578.69x = 4,981,260.22
5. Step 5: Solve for x
   x = 4,981,260.22/2,578.69
6. Step 6: Final answer
   x = 1,931.70