Finding the Third Proportional to 404.50 and 421.25

Step by Step Solution

1. Step 1: Write the proportion equation
   404.50 : 421.25 = 421.25 : x
2. Step 2: Convert to fraction form
   404.50/421.25 = 421.25/x
3. Step 3: Cross multiply
   404.50x = 421.25 × 421.25
4. Step 4: Simplify right side
   404.50x = 177,451.56
5. Step 5: Solve for x
   x = 177,451.56/404.50
6. Step 6: Final answer
   x = 438.69