Finding the Fourth Proportional to 1,439.92, 1,987.18 and 810.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.92 : 1,987.18 = 810.39 : x
2. Step 2: Convert to fraction form
   1,439.92/1,987.18 = 810.39/x
3. Step 3: Cross multiply
   1,439.92x = 1,987.18 × 810.39
4. Step 4: Simplify right side
   1,439.92x = 1,610,382.85
5. Step 5: Solve for x
   x = 1,610,382.85/1,439.92
6. Step 6: Final answer
   x = 1,118.39