Finding the Third Proportional to 81,729 and 128,020.50

Step by Step Solution

1. Step 1: Write the proportion equation
   81,729 : 128,020.50 = 128,020.50 : x
2. Step 2: Convert to fraction form
   81,729/128,020.50 = 128,020.50/x
3. Step 3: Cross multiply
   81,729x = 128,020.50 × 128,020.50
4. Step 4: Simplify right side
   81,729x = 16,389,248,420.25
5. Step 5: Solve for x
   x = 16,389,248,420.25/81,729
6. Step 6: Final answer
   x = 200,531.62