Finding the Third Proportional to 21,720 and 51,456

Step by Step Solution

1. Step 1: Write the proportion equation
   21,720 : 51,456 = 51,456 : x
2. Step 2: Convert to fraction form
   21,720/51,456 = 51,456/x
3. Step 3: Cross multiply
   21,720x = 51,456 × 51,456
4. Step 4: Simplify right side
   21,720x = 2,647,719,936
5. Step 5: Solve for x
   x = 2,647,719,936/21,720
6. Step 6: Final answer
   x = 121,902.39