Finding the Third Proportional to 300,456 and 639,216

Step by Step Solution

1. Step 1: Write the proportion equation
   300,456 : 639,216 = 639,216 : x
2. Step 2: Convert to fraction form
   300,456/639,216 = 639,216/x
3. Step 3: Cross multiply
   300,456x = 639,216 × 639,216
4. Step 4: Simplify right side
   300,456x = 408,597,094,656
5. Step 5: Solve for x
   x = 408,597,094,656/300,456
6. Step 6: Final answer
   x = 1,359,923.23