Finding the Third Proportional to 8,256 and 12,687

Step by Step Solution

1. Step 1: Write the proportion equation
   8,256 : 12,687 = 12,687 : x
2. Step 2: Convert to fraction form
   8,256/12,687 = 12,687/x
3. Step 3: Cross multiply
   8,256x = 12,687 × 12,687
4. Step 4: Simplify right side
   8,256x = 160,959,969
5. Step 5: Solve for x
   x = 160,959,969/8,256
6. Step 6: Final answer
   x = 19,496.12