Finding the Fourth Proportional to 1,020.83, 1,408.78 and 578.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.83 : 1,408.78 = 578.72 : x
2. Step 2: Convert to fraction form
   1,020.83/1,408.78 = 578.72/x
3. Step 3: Cross multiply
   1,020.83x = 1,408.78 × 578.72
4. Step 4: Simplify right side
   1,020.83x = 815,289.16
5. Step 5: Solve for x
   x = 815,289.16/1,020.83
6. Step 6: Final answer
   x = 798.65