Finding the Third Proportional to 305,128.50 and 638,143.50

Step by Step Solution

1. Step 1: Write the proportion equation
   305,128.50 : 638,143.50 = 638,143.50 : x
2. Step 2: Convert to fraction form
   305,128.50/638,143.50 = 638,143.50/x
3. Step 3: Cross multiply
   305,128.50x = 638,143.50 × 638,143.50
4. Step 4: Simplify right side
   305,128.50x = 407,227,126,592.25
5. Step 5: Solve for x
   x = 407,227,126,592.25/305,128.50
6. Step 6: Final answer
   x = 1,334,608.62