Finding the Third Proportional to 354.50 and 399.50

Step by Step Solution

1. Step 1: Write the proportion equation
   354.50 : 399.50 = 399.50 : x
2. Step 2: Convert to fraction form
   354.50/399.50 = 399.50/x
3. Step 3: Cross multiply
   354.50x = 399.50 × 399.50
4. Step 4: Simplify right side
   354.50x = 159,600.25
5. Step 5: Solve for x
   x = 159,600.25/354.50
6. Step 6: Final answer
   x = 450.21