Finding the Fourth Proportional to 1,139.31, 1,571.34 and 859.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.31 : 1,571.34 = 859.59 : x
2. Step 2: Convert to fraction form
   1,139.31/1,571.34 = 859.59/x
3. Step 3: Cross multiply
   1,139.31x = 1,571.34 × 859.59
4. Step 4: Simplify right side
   1,139.31x = 1,350,708.15
5. Step 5: Solve for x
   x = 1,350,708.15/1,139.31
6. Step 6: Final answer
   x = 1,185.55