Finding the Fourth Proportional to 2,616.38, 3,923.09 and 860.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,616.38 : 3,923.09 = 860.91 : x
2. Step 2: Convert to fraction form
   2,616.38/3,923.09 = 860.91/x
3. Step 3: Cross multiply
   2,616.38x = 3,923.09 × 860.91
4. Step 4: Simplify right side
   2,616.38x = 3,377,429.56
5. Step 5: Solve for x
   x = 3,377,429.56/2,616.38
6. Step 6: Final answer
   x = 1,290.88