Finding the Third Proportional to 393,601.50 and 815,211

Step by Step Solution

1. Step 1: Write the proportion equation
   393,601.50 : 815,211 = 815,211 : x
2. Step 2: Convert to fraction form
   393,601.50/815,211 = 815,211/x
3. Step 3: Cross multiply
   393,601.50x = 815,211 × 815,211
4. Step 4: Simplify right side
   393,601.50x = 664,568,974,521
5. Step 5: Solve for x
   x = 664,568,974,521/393,601.50
6. Step 6: Final answer
   x = 1,688,431.00