Finding the Third Proportional to 8,215.50 and 12,640.50

Step by Step Solution

1. Step 1: Write the proportion equation
   8,215.50 : 12,640.50 = 12,640.50 : x
2. Step 2: Convert to fraction form
   8,215.50/12,640.50 = 12,640.50/x
3. Step 3: Cross multiply
   8,215.50x = 12,640.50 × 12,640.50
4. Step 4: Simplify right side
   8,215.50x = 159,782,240.25
5. Step 5: Solve for x
   x = 159,782,240.25/8,215.50
6. Step 6: Final answer
   x = 19,448.88