Finding the Fourth Proportional to 8,111.50, 12,171.93 and 3,431.20

Step by Step Solution

1. Step 1: Write the proportion equation
   8,111.50 : 12,171.93 = 3,431.20 : x
2. Step 2: Convert to fraction form
   8,111.50/12,171.93 = 3,431.20/x
3. Step 3: Cross multiply
   8,111.50x = 12,171.93 × 3,431.20
4. Step 4: Simplify right side
   8,111.50x = 41,764,326.22
5. Step 5: Solve for x
   x = 41,764,326.22/8,111.50
6. Step 6: Final answer
   x = 5,148.78