Finding the Third Proportional to 639.56 and 747.56

Step by Step Solution

1. Step 1: Write the proportion equation
   639.56 : 747.56 = 747.56 : x
2. Step 2: Convert to fraction form
   639.56/747.56 = 747.56/x
3. Step 3: Cross multiply
   639.56x = 747.56 × 747.56
4. Step 4: Simplify right side
   639.56x = 558,849.69
5. Step 5: Solve for x
   x = 558,849.69/639.56
6. Step 6: Final answer
   x = 873.80