Finding the Third Proportional to 478.41 and 640.72

Step by Step Solution

1. Step 1: Write the proportion equation
   478.41 : 640.72 = 640.72 : x
2. Step 2: Convert to fraction form
   478.41/640.72 = 640.72/x
3. Step 3: Cross multiply
   478.41x = 640.72 × 640.72
4. Step 4: Simplify right side
   478.41x = 410,525.52
5. Step 5: Solve for x
   x = 410,525.52/478.41
6. Step 6: Final answer
   x = 858.11