Finding the Third Proportional to 315.56 and 646.31

Step by Step Solution

1. Step 1: Write the proportion equation
   315.56 : 646.31 = 646.31 : x
2. Step 2: Convert to fraction form
   315.56/646.31 = 646.31/x
3. Step 3: Cross multiply
   315.56x = 646.31 × 646.31
4. Step 4: Simplify right side
   315.56x = 417,719.85
5. Step 5: Solve for x
   x = 417,719.85/315.56
6. Step 6: Final answer
   x = 1,323.73