Finding the Third Proportional to 406.27 and 642.15

Step by Step Solution

1. Step 1: Write the proportion equation
   406.27 : 642.15 = 642.15 : x
2. Step 2: Convert to fraction form
   406.27/642.15 = 642.15/x
3. Step 3: Cross multiply
   406.27x = 642.15 × 642.15
4. Step 4: Simplify right side
   406.27x = 412,352.11
5. Step 5: Solve for x
   x = 412,352.11/406.27
6. Step 6: Final answer
   x = 1,014.98