Finding the Third Proportional to 640,456 and 1,379,880

Step by Step Solution

1. Step 1: Write the proportion equation
   640,456 : 1,379,880 = 1,379,880 : x
2. Step 2: Convert to fraction form
   640,456/1,379,880 = 1,379,880/x
3. Step 3: Cross multiply
   640,456x = 1,379,880 × 1,379,880
4. Step 4: Simplify right side
   640,456x = 1,904,068,814,400
5. Step 5: Solve for x
   x = 1,904,068,814,400/640,456
6. Step 6: Final answer
   x = 2,972,989.27