Finding the Fourth Proportional to 2,158.51, 3,240.20 and 860.89

Step by Step Solution

1. Step 1: Write the proportion equation
   2,158.51 : 3,240.20 = 860.89 : x
2. Step 2: Convert to fraction form
   2,158.51/3,240.20 = 860.89/x
3. Step 3: Cross multiply
   2,158.51x = 3,240.20 × 860.89
4. Step 4: Simplify right side
   2,158.51x = 2,789,455.78
5. Step 5: Solve for x
   x = 2,789,455.78/2,158.51
6. Step 6: Final answer
   x = 1,292.31