Finding the Fourth Proportional to 2,558.78, 3,531.16 and 1,439.56

Step by Step Solution

1. Step 1: Write the proportion equation
   2,558.78 : 3,531.16 = 1,439.56 : x
2. Step 2: Convert to fraction form
   2,558.78/3,531.16 = 1,439.56/x
3. Step 3: Cross multiply
   2,558.78x = 3,531.16 × 1,439.56
4. Step 4: Simplify right side
   2,558.78x = 5,083,316.69
5. Step 5: Solve for x
   x = 5,083,316.69/2,558.78
6. Step 6: Final answer
   x = 1,986.62