Finding the Third Proportional to 3,940.31 and 8,478.56

Step by Step Solution

1. Step 1: Write the proportion equation
   3,940.31 : 8,478.56 = 8,478.56 : x
2. Step 2: Convert to fraction form
   3,940.31/8,478.56 = 8,478.56/x
3. Step 3: Cross multiply
   3,940.31x = 8,478.56 × 8,478.56
4. Step 4: Simplify right side
   3,940.31x = 71,886,022.07
5. Step 5: Solve for x
   x = 71,886,022.07/3,940.31
6. Step 6: Final answer
   x = 18,243.74