Finding the Third Proportional to 21,990 and 53,151

Step by Step Solution

1. Step 1: Write the proportion equation
   21,990 : 53,151 = 53,151 : x
2. Step 2: Convert to fraction form
   21,990/53,151 = 53,151/x
3. Step 3: Cross multiply
   21,990x = 53,151 × 53,151
4. Step 4: Simplify right side
   21,990x = 2,825,028,801
5. Step 5: Solve for x
   x = 2,825,028,801/21,990
6. Step 6: Final answer
   x = 128,468.79