Finding the Fourth Proportional to 1,392.28, 1,921.39 and 802.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.28 : 1,921.39 = 802.80 : x
2. Step 2: Convert to fraction form
   1,392.28/1,921.39 = 802.80/x
3. Step 3: Cross multiply
   1,392.28x = 1,921.39 × 802.80
4. Step 4: Simplify right side
   1,392.28x = 1,542,489.89
5. Step 5: Solve for x
   x = 1,542,489.89/1,392.28
6. Step 6: Final answer
   x = 1,107.89