Finding the Fourth Proportional to 1,392.72, 1,920.96 and 868.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.72 : 1,920.96 = 868.56 : x
2. Step 2: Convert to fraction form
   1,392.72/1,920.96 = 868.56/x
3. Step 3: Cross multiply
   1,392.72x = 1,920.96 × 868.56
4. Step 4: Simplify right side
   1,392.72x = 1,668,469.02
5. Step 5: Solve for x
   x = 1,668,469.02/1,392.72
6. Step 6: Final answer
   x = 1,197.99