Finding the Third Proportional to 399.94 and 628.59

Step by Step Solution

1. Step 1: Write the proportion equation
   399.94 : 628.59 = 628.59 : x
2. Step 2: Convert to fraction form
   399.94/628.59 = 628.59/x
3. Step 3: Cross multiply
   399.94x = 628.59 × 628.59
4. Step 4: Simplify right side
   399.94x = 395,130.10
5. Step 5: Solve for x
   x = 395,130.10/399.94
6. Step 6: Final answer
   x = 987.98