Finding the Third Proportional to 399.38 and 514.69

Step by Step Solution

1. Step 1: Write the proportion equation
   399.38 : 514.69 = 514.69 : x
2. Step 2: Convert to fraction form
   399.38/514.69 = 514.69/x
3. Step 3: Cross multiply
   399.38x = 514.69 × 514.69
4. Step 4: Simplify right side
   399.38x = 264,903.22
5. Step 5: Solve for x
   x = 264,903.22/399.38
6. Step 6: Final answer
   x = 663.29