Finding the Third Proportional to 8,638.50 and 10,215.75

Step by Step Solution

1. Step 1: Write the proportion equation
   8,638.50 : 10,215.75 = 10,215.75 : x
2. Step 2: Convert to fraction form
   8,638.50/10,215.75 = 10,215.75/x
3. Step 3: Cross multiply
   8,638.50x = 10,215.75 × 10,215.75
4. Step 4: Simplify right side
   8,638.50x = 104,361,548.06
5. Step 5: Solve for x
   x = 104,361,548.06/8,638.50
6. Step 6: Final answer
   x = 12,080.98