Finding the Third Proportional to 309,919.50 and 678,807

Step by Step Solution

1. Step 1: Write the proportion equation
   309,919.50 : 678,807 = 678,807 : x
2. Step 2: Convert to fraction form
   309,919.50/678,807 = 678,807/x
3. Step 3: Cross multiply
   309,919.50x = 678,807 × 678,807
4. Step 4: Simplify right side
   309,919.50x = 460,778,943,249
5. Step 5: Solve for x
   x = 460,778,943,249/309,919.50
6. Step 6: Final answer
   x = 1,486,769.77