Finding the Fourth Proportional to 1,392.72, 1,921.90 and 803.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.72 : 1,921.90 = 803.36 : x
2. Step 2: Convert to fraction form
   1,392.72/1,921.90 = 803.36/x
3. Step 3: Cross multiply
   1,392.72x = 1,921.90 × 803.36
4. Step 4: Simplify right side
   1,392.72x = 1,543,977.58
5. Step 5: Solve for x
   x = 1,543,977.58/1,392.72
6. Step 6: Final answer
   x = 1,108.61