Finding the Third Proportional to 249,919 and 399,715.50

Step by Step Solution

1. Step 1: Write the proportion equation
   249,919 : 399,715.50 = 399,715.50 : x
2. Step 2: Convert to fraction form
   249,919/399,715.50 = 399,715.50/x
3. Step 3: Cross multiply
   249,919x = 399,715.50 × 399,715.50
4. Step 4: Simplify right side
   249,919x = 159,772,480,940.25
5. Step 5: Solve for x
   x = 159,772,480,940.25/249,919
6. Step 6: Final answer
   x = 639,297.06