Finding the Third Proportional to 639.56 and 704.81

Step by Step Solution

1. Step 1: Write the proportion equation
   639.56 : 704.81 = 704.81 : x
2. Step 2: Convert to fraction form
   639.56/704.81 = 704.81/x
3. Step 3: Cross multiply
   639.56x = 704.81 × 704.81
4. Step 4: Simplify right side
   639.56x = 496,760.66
5. Step 5: Solve for x
   x = 496,760.66/639.56
6. Step 6: Final answer
   x = 776.72