Finding the Fourth Proportional to 2,139.17, 3,208.77 and 822.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.17 : 3,208.77 = 822.78 : x
2. Step 2: Convert to fraction form
   2,139.17/3,208.77 = 822.78/x
3. Step 3: Cross multiply
   2,139.17x = 3,208.77 × 822.78
4. Step 4: Simplify right side
   2,139.17x = 2,640,111.78
5. Step 5: Solve for x
   x = 2,640,111.78/2,139.17
6. Step 6: Final answer
   x = 1,234.18