Finding the Third Proportional to 603.56 and 621.56

Step by Step Solution

1. Step 1: Write the proportion equation
   603.56 : 621.56 = 621.56 : x
2. Step 2: Convert to fraction form
   603.56/621.56 = 621.56/x
3. Step 3: Cross multiply
   603.56x = 621.56 × 621.56
4. Step 4: Simplify right side
   603.56x = 386,339.94
5. Step 5: Solve for x
   x = 386,339.94/603.56
6. Step 6: Final answer
   x = 640.10