Finding the Fourth Proportional to 2,158.68, 3,238.86 and 860.28

Step by Step Solution

1. Step 1: Write the proportion equation
   2,158.68 : 3,238.86 = 860.28 : x
2. Step 2: Convert to fraction form
   2,158.68/3,238.86 = 860.28/x
3. Step 3: Cross multiply
   2,158.68x = 3,238.86 × 860.28
4. Step 4: Simplify right side
   2,158.68x = 2,786,326.48
5. Step 5: Solve for x
   x = 2,786,326.48/2,158.68
6. Step 6: Final answer
   x = 1,290.75