Finding the Fourth Proportional to 1,439.12, 1,985.94 and 809.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.12 : 1,985.94 = 809.69 : x
2. Step 2: Convert to fraction form
   1,439.12/1,985.94 = 809.69/x
3. Step 3: Cross multiply
   1,439.12x = 1,985.94 × 809.69
4. Step 4: Simplify right side
   1,439.12x = 1,607,985.83
5. Step 5: Solve for x
   x = 1,607,985.83/1,439.12
6. Step 6: Final answer
   x = 1,117.34