Finding the Third Proportional to 388,144 and 617,216

Step by Step Solution

1. Step 1: Write the proportion equation
   388,144 : 617,216 = 617,216 : x
2. Step 2: Convert to fraction form
   388,144/617,216 = 617,216/x
3. Step 3: Cross multiply
   388,144x = 617,216 × 617,216
4. Step 4: Simplify right side
   388,144x = 380,955,590,656
5. Step 5: Solve for x
   x = 380,955,590,656/388,144
6. Step 6: Final answer
   x = 981,480.05