Finding the Third Proportional to 9,900 and 19,640

Step by Step Solution

1. Step 1: Write the proportion equation
   9,900 : 19,640 = 19,640 : x
2. Step 2: Convert to fraction form
   9,900/19,640 = 19,640/x
3. Step 3: Cross multiply
   9,900x = 19,640 × 19,640
4. Step 4: Simplify right side
   9,900x = 385,729,600
5. Step 5: Solve for x
   x = 385,729,600/9,900
6. Step 6: Final answer
   x = 38,962.59