Finding the Third Proportional to 351,817 and 686,136.50

Step by Step Solution

1. Step 1: Write the proportion equation
   351,817 : 686,136.50 = 686,136.50 : x
2. Step 2: Convert to fraction form
   351,817/686,136.50 = 686,136.50/x
3. Step 3: Cross multiply
   351,817x = 686,136.50 × 686,136.50
4. Step 4: Simplify right side
   351,817x = 470,783,296,632.25
5. Step 5: Solve for x
   x = 470,783,296,632.25/351,817
6. Step 6: Final answer
   x = 1,338,148.23