Finding the Fourth Proportional to 1,399.23, 1,930.94 and 809.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.23 : 1,930.94 = 809.78 : x
2. Step 2: Convert to fraction form
   1,399.23/1,930.94 = 809.78/x
3. Step 3: Cross multiply
   1,399.23x = 1,930.94 × 809.78
4. Step 4: Simplify right side
   1,399.23x = 1,563,625.93
5. Step 5: Solve for x
   x = 1,563,625.93/1,399.23
6. Step 6: Final answer
   x = 1,117.49