Finding the Third Proportional to 641.50 and 871.50

Step by Step Solution

1. Step 1: Write the proportion equation
   641.50 : 871.50 = 871.50 : x
2. Step 2: Convert to fraction form
   641.50/871.50 = 871.50/x
3. Step 3: Cross multiply
   641.50x = 871.50 × 871.50
4. Step 4: Simplify right side
   641.50x = 759,512.25
5. Step 5: Solve for x
   x = 759,512.25/641.50
6. Step 6: Final answer
   x = 1,183.96