Finding the Fourth Proportional to 1,399.05, 1,929.90 and 809.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.05 : 1,929.90 = 809.16 : x
2. Step 2: Convert to fraction form
   1,399.05/1,929.90 = 809.16/x
3. Step 3: Cross multiply
   1,399.05x = 1,929.90 × 809.16
4. Step 4: Simplify right side
   1,399.05x = 1,561,597.88
5. Step 5: Solve for x
   x = 1,561,597.88/1,399.05
6. Step 6: Final answer
   x = 1,116.18