Finding the Third Proportional to 259,699.50 and 398,641.50

Step by Step Solution

1. Step 1: Write the proportion equation
   259,699.50 : 398,641.50 = 398,641.50 : x
2. Step 2: Convert to fraction form
   259,699.50/398,641.50 = 398,641.50/x
3. Step 3: Cross multiply
   259,699.50x = 398,641.50 × 398,641.50
4. Step 4: Simplify right side
   259,699.50x = 158,915,045,522.25
5. Step 5: Solve for x
   x = 158,915,045,522.25/259,699.50
6. Step 6: Final answer
   x = 611,918.95