Finding the Fourth Proportional to 2,139.67, 3,209.71 and 679.04

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.67 : 3,209.71 = 679.04 : x
2. Step 2: Convert to fraction form
   2,139.67/3,209.71 = 679.04/x
3. Step 3: Cross multiply
   2,139.67x = 3,209.71 × 679.04
4. Step 4: Simplify right side
   2,139.67x = 2,179,521.48
5. Step 5: Solve for x
   x = 2,179,521.48/2,139.67
6. Step 6: Final answer
   x = 1,018.63