Finding the Third Proportional to 399,910 and 635,990

Step by Step Solution

1. Step 1: Write the proportion equation
   399,910 : 635,990 = 635,990 : x
2. Step 2: Convert to fraction form
   399,910/635,990 = 635,990/x
3. Step 3: Cross multiply
   399,910x = 635,990 × 635,990
4. Step 4: Simplify right side
   399,910x = 404,483,280,100
5. Step 5: Solve for x
   x = 404,483,280,100/399,910
6. Step 6: Final answer
   x = 1,011,435.77