Finding the Fourth Proportional to 1,392.18, 1,921.90 and 868.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.18 : 1,921.90 = 868.38 : x
2. Step 2: Convert to fraction form
   1,392.18/1,921.90 = 868.38/x
3. Step 3: Cross multiply
   1,392.18x = 1,921.90 × 868.38
4. Step 4: Simplify right side
   1,392.18x = 1,668,939.52
5. Step 5: Solve for x
   x = 1,668,939.52/1,392.18
6. Step 6: Final answer
   x = 1,198.80