Finding the Fourth Proportional to 1,116.12, 1,540.31 and 618.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,116.12 : 1,540.31 = 618.78 : x
2. Step 2: Convert to fraction form
   1,116.12/1,540.31 = 618.78/x
3. Step 3: Cross multiply
   1,116.12x = 1,540.31 × 618.78
4. Step 4: Simplify right side
   1,116.12x = 953,113.02
5. Step 5: Solve for x
   x = 953,113.02/1,116.12
6. Step 6: Final answer
   x = 853.95