Finding the Third Proportional to 8,215 and 12,642

Step by Step Solution

1. Step 1: Write the proportion equation
   8,215 : 12,642 = 12,642 : x
2. Step 2: Convert to fraction form
   8,215/12,642 = 12,642/x
3. Step 3: Cross multiply
   8,215x = 12,642 × 12,642
4. Step 4: Simplify right side
   8,215x = 159,820,164
5. Step 5: Solve for x
   x = 159,820,164/8,215
6. Step 6: Final answer
   x = 19,454.68