Finding the Fourth Proportional to 1,439.37, 1,987.98 and 1,020.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.37 : 1,987.98 = 1,020.78 : x
2. Step 2: Convert to fraction form
   1,439.37/1,987.98 = 1,020.78/x
3. Step 3: Cross multiply
   1,439.37x = 1,987.98 × 1,020.78
4. Step 4: Simplify right side
   1,439.37x = 2,029,290.22
5. Step 5: Solve for x
   x = 2,029,290.22/1,439.37
6. Step 6: Final answer
   x = 1,409.85