Finding the Fourth Proportional to 1,128.31, 1,559.06 and 868.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,128.31 : 1,559.06 = 868.57 : x
2. Step 2: Convert to fraction form
   1,128.31/1,559.06 = 868.57/x
3. Step 3: Cross multiply
   1,128.31x = 1,559.06 × 868.57
4. Step 4: Simplify right side
   1,128.31x = 1,354,152.74
5. Step 5: Solve for x
   x = 1,354,152.74/1,128.31
6. Step 6: Final answer
   x = 1,200.16