Finding the Third Proportional to 312,521 and 647,200

Step by Step Solution

1. Step 1: Write the proportion equation
   312,521 : 647,200 = 647,200 : x
2. Step 2: Convert to fraction form
   312,521/647,200 = 647,200/x
3. Step 3: Cross multiply
   312,521x = 647,200 × 647,200
4. Step 4: Simplify right side
   312,521x = 418,867,840,000
5. Step 5: Solve for x
   x = 418,867,840,000/312,521
6. Step 6: Final answer
   x = 1,340,287.02