Finding the Fourth Proportional to 2,639.38, 3,957.79 and 1,078.76

Step by Step Solution

1. Step 1: Write the proportion equation
   2,639.38 : 3,957.79 = 1,078.76 : x
2. Step 2: Convert to fraction form
   2,639.38/3,957.79 = 1,078.76/x
3. Step 3: Cross multiply
   2,639.38x = 3,957.79 × 1,078.76
4. Step 4: Simplify right side
   2,639.38x = 4,269,500.15
5. Step 5: Solve for x
   x = 4,269,500.15/2,639.38
6. Step 6: Final answer
   x = 1,617.61