Finding the Third Proportional to 424.50 and 644.50

Step by Step Solution

1. Step 1: Write the proportion equation
   424.50 : 644.50 = 644.50 : x
2. Step 2: Convert to fraction form
   424.50/644.50 = 644.50/x
3. Step 3: Cross multiply
   424.50x = 644.50 × 644.50
4. Step 4: Simplify right side
   424.50x = 415,380.25
5. Step 5: Solve for x
   x = 415,380.25/424.50
6. Step 6: Final answer
   x = 978.52