Finding the Third Proportional to 128,200.50 and 199,021.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,200.50 : 199,021.50 = 199,021.50 : x
2. Step 2: Convert to fraction form
   128,200.50/199,021.50 = 199,021.50/x
3. Step 3: Cross multiply
   128,200.50x = 199,021.50 × 199,021.50
4. Step 4: Simplify right side
   128,200.50x = 39,609,557,462.25
5. Step 5: Solve for x
   x = 39,609,557,462.25/128,200.50
6. Step 6: Final answer
   x = 308,965.70