Finding the Fourth Proportional to 1,078.71, 1,487.61 and 858.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,078.71 : 1,487.61 = 858.39 : x
2. Step 2: Convert to fraction form
   1,078.71/1,487.61 = 858.39/x
3. Step 3: Cross multiply
   1,078.71x = 1,487.61 × 858.39
4. Step 4: Simplify right side
   1,078.71x = 1,276,949.55
5. Step 5: Solve for x
   x = 1,276,949.55/1,078.71
6. Step 6: Final answer
   x = 1,183.77