Finding the Third Proportional to 318.09 and 665.72

Step by Step Solution

1. Step 1: Write the proportion equation
   318.09 : 665.72 = 665.72 : x
2. Step 2: Convert to fraction form
   318.09/665.72 = 665.72/x
3. Step 3: Cross multiply
   318.09x = 665.72 × 665.72
4. Step 4: Simplify right side
   318.09x = 443,181.45
5. Step 5: Solve for x
   x = 443,181.45/318.09
6. Step 6: Final answer
   x = 1,393.24