Finding the Third Proportional to 9,900 and 20,619

Step by Step Solution

1. Step 1: Write the proportion equation
   9,900 : 20,619 = 20,619 : x
2. Step 2: Convert to fraction form
   9,900/20,619 = 20,619/x
3. Step 3: Cross multiply
   9,900x = 20,619 × 20,619
4. Step 4: Simplify right side
   9,900x = 425,143,161
5. Step 5: Solve for x
   x = 425,143,161/9,900
6. Step 6: Final answer
   x = 42,943.75