Finding the Fourth Proportional to 3,906.72, 5,391.12 and 2,138.32

Step by Step Solution

1. Step 1: Write the proportion equation
   3,906.72 : 5,391.12 = 2,138.32 : x
2. Step 2: Convert to fraction form
   3,906.72/5,391.12 = 2,138.32/x
3. Step 3: Cross multiply
   3,906.72x = 5,391.12 × 2,138.32
4. Step 4: Simplify right side
   3,906.72x = 11,527,939.72
5. Step 5: Solve for x
   x = 11,527,939.72/3,906.72
6. Step 6: Final answer
   x = 2,950.80