Finding the Fourth Proportional to 3,916.20, 5,405.83 and 2,591.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,916.20 : 5,405.83 = 2,591.72 : x
2. Step 2: Convert to fraction form
   3,916.20/5,405.83 = 2,591.72/x
3. Step 3: Cross multiply
   3,916.20x = 5,405.83 × 2,591.72
4. Step 4: Simplify right side
   3,916.20x = 14,010,397.73
5. Step 5: Solve for x
   x = 14,010,397.73/3,916.20
6. Step 6: Final answer
   x = 3,577.55