Finding the Fourth Proportional to 2,621.06, 3,929.89 and 1,389.05

Step by Step Solution

1. Step 1: Write the proportion equation
   2,621.06 : 3,929.89 = 1,389.05 : x
2. Step 2: Convert to fraction form
   2,621.06/3,929.89 = 1,389.05/x
3. Step 3: Cross multiply
   2,621.06x = 3,929.89 × 1,389.05
4. Step 4: Simplify right side
   2,621.06x = 5,458,790.58
5. Step 5: Solve for x
   x = 5,458,790.58/2,621.06
6. Step 6: Final answer
   x = 2,082.67