Finding the Third Proportional to 128,424 and 199,630.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,424 : 199,630.50 = 199,630.50 : x
2. Step 2: Convert to fraction form
   128,424/199,630.50 = 199,630.50/x
3. Step 3: Cross multiply
   128,424x = 199,630.50 × 199,630.50
4. Step 4: Simplify right side
   128,424x = 39,852,336,530.25
5. Step 5: Solve for x
   x = 39,852,336,530.25/128,424
6. Step 6: Final answer
   x = 310,318.45