Finding the Fourth Proportional to 2,105.31, 3,158.34 and 718.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,105.31 : 3,158.34 = 718.80 : x
2. Step 2: Convert to fraction form
   2,105.31/3,158.34 = 718.80/x
3. Step 3: Cross multiply
   2,105.31x = 3,158.34 × 718.80
4. Step 4: Simplify right side
   2,105.31x = 2,270,214.79
5. Step 5: Solve for x
   x = 2,270,214.79/2,105.31
6. Step 6: Final answer
   x = 1,078.33