Finding the Fourth Proportional to 3,906.89, 5,391.64 and 2,138.50

Step by Step Solution

1. Step 1: Write the proportion equation
   3,906.89 : 5,391.64 = 2,138.50 : x
2. Step 2: Convert to fraction form
   3,906.89/5,391.64 = 2,138.50/x
3. Step 3: Cross multiply
   3,906.89x = 5,391.64 × 2,138.50
4. Step 4: Simplify right side
   3,906.89x = 11,530,031.55
5. Step 5: Solve for x
   x = 11,530,031.55/3,906.89
6. Step 6: Final answer
   x = 2,951.20