Finding the Fourth Proportional to 1,144.11, 1,578.89 and 620.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,144.11 : 1,578.89 = 620.15 : x
2. Step 2: Convert to fraction form
   1,144.11/1,578.89 = 620.15/x
3. Step 3: Cross multiply
   1,144.11x = 1,578.89 × 620.15
4. Step 4: Simplify right side
   1,144.11x = 979,137.64
5. Step 5: Solve for x
   x = 979,137.64/1,144.11
6. Step 6: Final answer
   x = 855.81