Finding the Third Proportional to 315,665.50 and 690,380

Step by Step Solution

1. Step 1: Write the proportion equation
   315,665.50 : 690,380 = 690,380 : x
2. Step 2: Convert to fraction form
   315,665.50/690,380 = 690,380/x
3. Step 3: Cross multiply
   315,665.50x = 690,380 × 690,380
4. Step 4: Simplify right side
   315,665.50x = 476,624,544,400
5. Step 5: Solve for x
   x = 476,624,544,400/315,665.50
6. Step 6: Final answer
   x = 1,509,903.82