Finding the Fourth Proportional to 2,558.79, 3,531.06 and 1,439.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,558.79 : 3,531.06 = 1,439.78 : x
2. Step 2: Convert to fraction form
   2,558.79/3,531.06 = 1,439.78/x
3. Step 3: Cross multiply
   2,558.79x = 3,531.06 × 1,439.78
4. Step 4: Simplify right side
   2,558.79x = 5,083,931.91
5. Step 5: Solve for x
   x = 5,083,931.91/2,558.79
6. Step 6: Final answer
   x = 1,986.85