Finding the Fourth Proportional to 1,020.55, 1,408.62 and 578.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.55 : 1,408.62 = 578.72 : x
2. Step 2: Convert to fraction form
   1,020.55/1,408.62 = 578.72/x
3. Step 3: Cross multiply
   1,020.55x = 1,408.62 × 578.72
4. Step 4: Simplify right side
   1,020.55x = 815,196.57
5. Step 5: Solve for x
   x = 815,196.57/1,020.55
6. Step 6: Final answer
   x = 798.78