Finding the Fourth Proportional to 3,940.71, 5,438.12 and 2,172.48

Step by Step Solution

1. Step 1: Write the proportion equation
   3,940.71 : 5,438.12 = 2,172.48 : x
2. Step 2: Convert to fraction form
   3,940.71/5,438.12 = 2,172.48/x
3. Step 3: Cross multiply
   3,940.71x = 5,438.12 × 2,172.48
4. Step 4: Simplify right side
   3,940.71x = 11,814,196.08
5. Step 5: Solve for x
   x = 11,814,196.08/3,940.71
6. Step 6: Final answer
   x = 2,997.99