Finding the Third Proportional to 9,990 and 21,900

Step by Step Solution

1. Step 1: Write the proportion equation
   9,990 : 21,900 = 21,900 : x
2. Step 2: Convert to fraction form
   9,990/21,900 = 21,900/x
3. Step 3: Cross multiply
   9,990x = 21,900 × 21,900
4. Step 4: Simplify right side
   9,990x = 479,610,000
5. Step 5: Solve for x
   x = 479,610,000/9,990
6. Step 6: Final answer
   x = 48,009.01