Finding the Fourth Proportional to 3,940.78, 5,437.86 and 2,172.28

Step by Step Solution

1. Step 1: Write the proportion equation
   3,940.78 : 5,437.86 = 2,172.28 : x
2. Step 2: Convert to fraction form
   3,940.78/5,437.86 = 2,172.28/x
3. Step 3: Cross multiply
   3,940.78x = 5,437.86 × 2,172.28
4. Step 4: Simplify right side
   3,940.78x = 11,812,554.52
5. Step 5: Solve for x
   x = 11,812,554.52/3,940.78
6. Step 6: Final answer
   x = 2,997.52