Finding the Third Proportional to 12,978 and 20,655

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978 : 20,655 = 20,655 : x
2. Step 2: Convert to fraction form
   12,978/20,655 = 20,655/x
3. Step 3: Cross multiply
   12,978x = 20,655 × 20,655
4. Step 4: Simplify right side
   12,978x = 426,629,025
5. Step 5: Solve for x
   x = 426,629,025/12,978
6. Step 6: Final answer
   x = 32,873.25