Finding the Fourth Proportional to 3,920.72, 5,422.61 and 3,855.11

Step by Step Solution

1. Step 1: Write the proportion equation
   3,920.72 : 5,422.61 = 3,855.11 : x
2. Step 2: Convert to fraction form
   3,920.72/5,422.61 = 3,855.11/x
3. Step 3: Cross multiply
   3,920.72x = 5,422.61 × 3,855.11
4. Step 4: Simplify right side
   3,920.72x = 20,904,738.76
5. Step 5: Solve for x
   x = 20,904,738.76/3,920.72
6. Step 6: Final answer
   x = 5,331.86