Finding the Fourth Proportional to 1,020.67, 1,408.61 and 578.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,020.67 : 1,408.61 = 578.71 : x
2. Step 2: Convert to fraction form
   1,020.67/1,408.61 = 578.71/x
3. Step 3: Cross multiply
   1,020.67x = 1,408.61 × 578.71
4. Step 4: Simplify right side
   1,020.67x = 815,174.62
5. Step 5: Solve for x
   x = 815,174.62/1,020.67
6. Step 6: Final answer
   x = 798.67