Finding the Fourth Proportional to 3,418.54, 5,128.20 and 1,078.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,418.54 : 5,128.20 = 1,078.72 : x
2. Step 2: Convert to fraction form
   3,418.54/5,128.20 = 1,078.72/x
3. Step 3: Cross multiply
   3,418.54x = 5,128.20 × 1,078.72
4. Step 4: Simplify right side
   3,418.54x = 5,531,891.90
5. Step 5: Solve for x
   x = 5,531,891.90/3,418.54
6. Step 6: Final answer
   x = 1,618.20