Finding the Fourth Proportional to 1,392.89, 1,921.24 and 803.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.89 : 1,921.24 = 803.21 : x
2. Step 2: Convert to fraction form
   1,392.89/1,921.24 = 803.21/x
3. Step 3: Cross multiply
   1,392.89x = 1,921.24 × 803.21
4. Step 4: Simplify right side
   1,392.89x = 1,543,161.98
5. Step 5: Solve for x
   x = 1,543,161.98/1,392.89
6. Step 6: Final answer
   x = 1,107.88