Finding the Fourth Proportional to 1,382.58, 1,906.65 and 858.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,382.58 : 1,906.65 = 858.78 : x
2. Step 2: Convert to fraction form
   1,382.58/1,906.65 = 858.78/x
3. Step 3: Cross multiply
   1,382.58x = 1,906.65 × 858.78
4. Step 4: Simplify right side
   1,382.58x = 1,637,392.89
5. Step 5: Solve for x
   x = 1,637,392.89/1,382.58
6. Step 6: Final answer
   x = 1,184.30