Finding the Third Proportional to 85,721 and 128,499

Step by Step Solution

1. Step 1: Write the proportion equation
   85,721 : 128,499 = 128,499 : x
2. Step 2: Convert to fraction form
   85,721/128,499 = 128,499/x
3. Step 3: Cross multiply
   85,721x = 128,499 × 128,499
4. Step 4: Simplify right side
   85,721x = 16,511,993,001
5. Step 5: Solve for x
   x = 16,511,993,001/85,721
6. Step 6: Final answer
   x = 192,624.83