Finding the Fourth Proportional to 3,899.72, 5,381.55 and 2,131.33

Step by Step Solution

1. Step 1: Write the proportion equation
   3,899.72 : 5,381.55 = 2,131.33 : x
2. Step 2: Convert to fraction form
   3,899.72/5,381.55 = 2,131.33/x
3. Step 3: Cross multiply
   3,899.72x = 5,381.55 × 2,131.33
4. Step 4: Simplify right side
   3,899.72x = 11,469,858.96
5. Step 5: Solve for x
   x = 11,469,858.96/3,899.72
6. Step 6: Final answer
   x = 2,941.20