Finding the Third Proportional to 19,899 and 21,721.50

Step by Step Solution

1. Step 1: Write the proportion equation
   19,899 : 21,721.50 = 21,721.50 : x
2. Step 2: Convert to fraction form
   19,899/21,721.50 = 21,721.50/x
3. Step 3: Cross multiply
   19,899x = 21,721.50 × 21,721.50
4. Step 4: Simplify right side
   19,899x = 471,823,562.25
5. Step 5: Solve for x
   x = 471,823,562.25/19,899
6. Step 6: Final answer
   x = 23,710.92