Finding the Fourth Proportional to 2,139.49, 3,208.23 and 678.73

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.49 : 3,208.23 = 678.73 : x
2. Step 2: Convert to fraction form
   2,139.49/3,208.23 = 678.73/x
3. Step 3: Cross multiply
   2,139.49x = 3,208.23 × 678.73
4. Step 4: Simplify right side
   2,139.49x = 2,177,521.95
5. Step 5: Solve for x
   x = 2,177,521.95/2,139.49
6. Step 6: Final answer
   x = 1,017.78