Finding the Third Proportional to 300.25 and 639.25

Step by Step Solution

1. Step 1: Write the proportion equation
   300.25 : 639.25 = 639.25 : x
2. Step 2: Convert to fraction form
   300.25/639.25 = 639.25/x
3. Step 3: Cross multiply
   300.25x = 639.25 × 639.25
4. Step 4: Simplify right side
   300.25x = 408,640.56
5. Step 5: Solve for x
   x = 408,640.56/300.25
6. Step 6: Final answer
   x = 1,361.00