Finding the Third Proportional to 311.48 and 648.56

Step by Step Solution

1. Step 1: Write the proportion equation
   311.48 : 648.56 = 648.56 : x
2. Step 2: Convert to fraction form
   311.48/648.56 = 648.56/x
3. Step 3: Cross multiply
   311.48x = 648.56 × 648.56
4. Step 4: Simplify right side
   311.48x = 420,633.32
5. Step 5: Solve for x
   x = 420,633.32/311.48
6. Step 6: Final answer
   x = 1,350.42