Finding the Third Proportional to 128,418 and 199,621.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,418 : 199,621.50 = 199,621.50 : x
2. Step 2: Convert to fraction form
   128,418/199,621.50 = 199,621.50/x
3. Step 3: Cross multiply
   128,418x = 199,621.50 × 199,621.50
4. Step 4: Simplify right side
   128,418x = 39,848,743,262.25
5. Step 5: Solve for x
   x = 39,848,743,262.25/128,418
6. Step 6: Final answer
   x = 310,304.97