Finding the Third Proportional to 10,215 and 21,690

Step by Step Solution

1. Step 1: Write the proportion equation
   10,215 : 21,690 = 21,690 : x
2. Step 2: Convert to fraction form
   10,215/21,690 = 21,690/x
3. Step 3: Cross multiply
   10,215x = 21,690 × 21,690
4. Step 4: Simplify right side
   10,215x = 470,456,100
5. Step 5: Solve for x
   x = 470,456,100/10,215
6. Step 6: Final answer
   x = 46,055.42