Finding the Fourth Proportional to 1,399.30, 1,931.19 and 809.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.30 : 1,931.19 = 809.82 : x
2. Step 2: Convert to fraction form
   1,399.30/1,931.19 = 809.82/x
3. Step 3: Cross multiply
   1,399.30x = 1,931.19 × 809.82
4. Step 4: Simplify right side
   1,399.30x = 1,563,916.29
5. Step 5: Solve for x
   x = 1,563,916.29/1,399.30
6. Step 6: Final answer
   x = 1,117.64