Finding the Third Proportional to 149,128.50 and 320,500.50

Step by Step Solution

1. Step 1: Write the proportion equation
   149,128.50 : 320,500.50 = 320,500.50 : x
2. Step 2: Convert to fraction form
   149,128.50/320,500.50 = 320,500.50/x
3. Step 3: Cross multiply
   149,128.50x = 320,500.50 × 320,500.50
4. Step 4: Simplify right side
   149,128.50x = 102,720,570,500.25
5. Step 5: Solve for x
   x = 102,720,570,500.25/149,128.50
6. Step 6: Final answer
   x = 688,805.76