Finding the Fourth Proportional to 1,439.21, 1,986.18 and 809.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.21 : 1,986.18 = 809.75 : x
2. Step 2: Convert to fraction form
   1,439.21/1,986.18 = 809.75/x
3. Step 3: Cross multiply
   1,439.21x = 1,986.18 × 809.75
4. Step 4: Simplify right side
   1,439.21x = 1,608,309.26
5. Step 5: Solve for x
   x = 1,608,309.26/1,439.21
6. Step 6: Final answer
   x = 1,117.49