Finding the Fourth Proportional to 2,139.09, 3,208.83 and 840.25

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.09 : 3,208.83 = 840.25 : x
2. Step 2: Convert to fraction form
   2,139.09/3,208.83 = 840.25/x
3. Step 3: Cross multiply
   2,139.09x = 3,208.83 × 840.25
4. Step 4: Simplify right side
   2,139.09x = 2,696,219.41
5. Step 5: Solve for x
   x = 2,696,219.41/2,139.09
6. Step 6: Final answer
   x = 1,260.45