Finding the Fourth Proportional to 3,906.86, 5,391.46 and 2,138.57

Step by Step Solution

1. Step 1: Write the proportion equation
   3,906.86 : 5,391.46 = 2,138.57 : x
2. Step 2: Convert to fraction form
   3,906.86/5,391.46 = 2,138.57/x
3. Step 3: Cross multiply
   3,906.86x = 5,391.46 × 2,138.57
4. Step 4: Simplify right side
   3,906.86x = 11,530,010.55
5. Step 5: Solve for x
   x = 11,530,010.55/3,906.86
6. Step 6: Final answer
   x = 2,951.23