Finding the Third Proportional to 351,855 and 686,209.50

Step by Step Solution

1. Step 1: Write the proportion equation
   351,855 : 686,209.50 = 686,209.50 : x
2. Step 2: Convert to fraction form
   351,855/686,209.50 = 686,209.50/x
3. Step 3: Cross multiply
   351,855x = 686,209.50 × 686,209.50
4. Step 4: Simplify right side
   351,855x = 470,883,477,890.25
5. Step 5: Solve for x
   x = 470,883,477,890.25/351,855
6. Step 6: Final answer
   x = 1,338,288.44