Finding the Third Proportional to 389,422.69 and 617,485.78

Step by Step Solution

1. Step 1: Write the proportion equation
   389,422.69 : 617,485.78 = 617,485.78 : x
2. Step 2: Convert to fraction form
   389,422.69/617,485.78 = 617,485.78/x
3. Step 3: Cross multiply
   389,422.69x = 617,485.78 × 617,485.78
4. Step 4: Simplify right side
   389,422.69x = 381,288,690,045.92
5. Step 5: Solve for x
   x = 381,288,690,045.92/389,422.69
6. Step 6: Final answer
   x = 979,112.68