Finding the Third Proportional to 21,870 and 51,399

Step by Step Solution

1. Step 1: Write the proportion equation
   21,870 : 51,399 = 51,399 : x
2. Step 2: Convert to fraction form
   21,870/51,399 = 51,399/x
3. Step 3: Cross multiply
   21,870x = 51,399 × 51,399
4. Step 4: Simplify right side
   21,870x = 2,641,857,201
5. Step 5: Solve for x
   x = 2,641,857,201/21,870
6. Step 6: Final answer
   x = 120,798.23