Finding the Fourth Proportional to 1,399.34, 1,931.14 and 809.92

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.34 : 1,931.14 = 809.92 : x
2. Step 2: Convert to fraction form
   1,399.34/1,931.14 = 809.92/x
3. Step 3: Cross multiply
   1,399.34x = 1,931.14 × 809.92
4. Step 4: Simplify right side
   1,399.34x = 1,564,068.91
5. Step 5: Solve for x
   x = 1,564,068.91/1,399.34
6. Step 6: Final answer
   x = 1,117.72