Finding the Third Proportional to 317,890.50 and 690,456

Step by Step Solution

1. Step 1: Write the proportion equation
   317,890.50 : 690,456 = 690,456 : x
2. Step 2: Convert to fraction form
   317,890.50/690,456 = 690,456/x
3. Step 3: Cross multiply
   317,890.50x = 690,456 × 690,456
4. Step 4: Simplify right side
   317,890.50x = 476,729,487,936
5. Step 5: Solve for x
   x = 476,729,487,936/317,890.50
6. Step 6: Final answer
   x = 1,499,665.73