Finding the Fourth Proportional to 1,391.40, 2,086.86 and 806.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.40 : 2,086.86 = 806.04 : x
2. Step 2: Convert to fraction form
   1,391.40/2,086.86 = 806.04/x
3. Step 3: Cross multiply
   1,391.40x = 2,086.86 × 806.04
4. Step 4: Simplify right side
   1,391.40x = 1,682,092.63
5. Step 5: Solve for x
   x = 1,682,092.63/1,391.40
6. Step 6: Final answer
   x = 1,208.92