Finding the Third Proportional to 300.38 and 639.56

Step by Step Solution

1. Step 1: Write the proportion equation
   300.38 : 639.56 = 639.56 : x
2. Step 2: Convert to fraction form
   300.38/639.56 = 639.56/x
3. Step 3: Cross multiply
   300.38x = 639.56 × 639.56
4. Step 4: Simplify right side
   300.38x = 409,040.19
5. Step 5: Solve for x
   x = 409,040.19/300.38
6. Step 6: Final answer
   x = 1,361.77