Finding the Fourth Proportional to 2,158.90, 3,238.56 and 860.06

Step by Step Solution

1. Step 1: Write the proportion equation
   2,158.90 : 3,238.56 = 860.06 : x
2. Step 2: Convert to fraction form
   2,158.90/3,238.56 = 860.06/x
3. Step 3: Cross multiply
   2,158.90x = 3,238.56 × 860.06
4. Step 4: Simplify right side
   2,158.90x = 2,785,364.01
5. Step 5: Solve for x
   x = 2,785,364.01/2,158.90
6. Step 6: Final answer
   x = 1,290.18