Finding the Fourth Proportional to 2,105.31, 3,158.09 and 872.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.31 : 3,158.09 = 872.81 : x
2. Step 2: Convert to fraction form
   2,105.31/3,158.09 = 872.81/x
3. Step 3: Cross multiply
   2,105.31x = 3,158.09 × 872.81
4. Step 4: Simplify right side
   2,105.31x = 2,756,412.53
5. Step 5: Solve for x
   x = 2,756,412.53/2,105.31
6. Step 6: Final answer
   x = 1,309.27