Finding the Fourth Proportional to 1,382.85, 1,908.23 and 858.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,382.85 : 1,908.23 = 858.78 : x
2. Step 2: Convert to fraction form
   1,382.85/1,908.23 = 858.78/x
3. Step 3: Cross multiply
   1,382.85x = 1,908.23 × 858.78
4. Step 4: Simplify right side
   1,382.85x = 1,638,745.47
5. Step 5: Solve for x
   x = 1,638,745.47/1,382.85
6. Step 6: Final answer
   x = 1,185.05