Finding the Third Proportional to 255.50 and 404.25

Step by Step Solution

1. Step 1: Write the proportion equation
   255.50 : 404.25 = 404.25 : x
2. Step 2: Convert to fraction form
   255.50/404.25 = 404.25/x
3. Step 3: Cross multiply
   255.50x = 404.25 × 404.25
4. Step 4: Simplify right side
   255.50x = 163,418.06
5. Step 5: Solve for x
   x = 163,418.06/255.50
6. Step 6: Final answer
   x = 639.60