Finding the Third Proportional to 255.38 and 397.69

Step by Step Solution

1. Step 1: Write the proportion equation
   255.38 : 397.69 = 397.69 : x
2. Step 2: Convert to fraction form
   255.38/397.69 = 397.69/x
3. Step 3: Cross multiply
   255.38x = 397.69 × 397.69
4. Step 4: Simplify right side
   255.38x = 158,155.35
5. Step 5: Solve for x
   x = 158,155.35/255.38
6. Step 6: Final answer
   x = 619.31