Finding the Fourth Proportional to 2,581.17, 3,872.21 and 826.55

Step by Step Solution

1. Step 1: Write the proportion equation
   2,581.17 : 3,872.21 = 826.55 : x
2. Step 2: Convert to fraction form
   2,581.17/3,872.21 = 826.55/x
3. Step 3: Cross multiply
   2,581.17x = 3,872.21 × 826.55
4. Step 4: Simplify right side
   2,581.17x = 3,200,587.98
5. Step 5: Solve for x
   x = 3,200,587.98/2,581.17
6. Step 6: Final answer
   x = 1,239.98