Finding the Fourth Proportional to 2,105.80, 3,153.90 and 1,328.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.80 : 3,153.90 = 1,328.20 : x
2. Step 2: Convert to fraction form
   2,105.80/3,153.90 = 1,328.20/x
3. Step 3: Cross multiply
   2,105.80x = 3,153.90 × 1,328.20
4. Step 4: Simplify right side
   2,105.80x = 4,189,009.98
5. Step 5: Solve for x
   x = 4,189,009.98/2,105.80
6. Step 6: Final answer
   x = 1,989.27