Finding the Third Proportional to 399.50 and 504.50

Step by Step Solution

1. Step 1: Write the proportion equation
   399.50 : 504.50 = 504.50 : x
2. Step 2: Convert to fraction form
   399.50/504.50 = 504.50/x
3. Step 3: Cross multiply
   399.50x = 504.50 × 504.50
4. Step 4: Simplify right side
   399.50x = 254,520.25
5. Step 5: Solve for x
   x = 254,520.25/399.50
6. Step 6: Final answer
   x = 637.10