Finding the Fourth Proportional to 1,391.92, 1,920.83 and 802.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.92 : 1,920.83 = 802.55 : x
2. Step 2: Convert to fraction form
   1,391.92/1,920.83 = 802.55/x
3. Step 3: Cross multiply
   1,391.92x = 1,920.83 × 802.55
4. Step 4: Simplify right side
   1,391.92x = 1,541,562.91
5. Step 5: Solve for x
   x = 1,541,562.91/1,391.92
6. Step 6: Final answer
   x = 1,107.51