Finding the Fourth Proportional to 3,559.48, 5,328.72 and 2,639.20

Step by Step Solution

1. Step 1: Write the proportion equation
   3,559.48 : 5,328.72 = 2,639.20 : x
2. Step 2: Convert to fraction form
   3,559.48/5,328.72 = 2,639.20/x
3. Step 3: Cross multiply
   3,559.48x = 5,328.72 × 2,639.20
4. Step 4: Simplify right side
   3,559.48x = 14,063,557.82
5. Step 5: Solve for x
   x = 14,063,557.82/3,559.48
6. Step 6: Final answer
   x = 3,951.01