Finding the Fourth Proportional to 2,623.35, 3,929.90 and 1,389.06

Step by Step Solution

1. Step 1: Write the proportion equation
   2,623.35 : 3,929.90 = 1,389.06 : x
2. Step 2: Convert to fraction form
   2,623.35/3,929.90 = 1,389.06/x
3. Step 3: Cross multiply
   2,623.35x = 3,929.90 × 1,389.06
4. Step 4: Simplify right side
   2,623.35x = 5,458,866.89
5. Step 5: Solve for x
   x = 5,458,866.89/2,623.35
6. Step 6: Final answer
   x = 2,080.88