Finding the Fourth Proportional to 2,025.78, 3,039.14 and 639.10

Step by Step Solution

1. Step 1: Write the proportion equation
   2,025.78 : 3,039.14 = 639.10 : x
2. Step 2: Convert to fraction form
   2,025.78/3,039.14 = 639.10/x
3. Step 3: Cross multiply
   2,025.78x = 3,039.14 × 639.10
4. Step 4: Simplify right side
   2,025.78x = 1,942,314.37
5. Step 5: Solve for x
   x = 1,942,314.37/2,025.78
6. Step 6: Final answer
   x = 958.80