Finding the Third Proportional to 423,642 and 648,990

Step by Step Solution

1. Step 1: Write the proportion equation
   423,642 : 648,990 = 648,990 : x
2. Step 2: Convert to fraction form
   423,642/648,990 = 648,990/x
3. Step 3: Cross multiply
   423,642x = 648,990 × 648,990
4. Step 4: Simplify right side
   423,642x = 421,188,020,100
5. Step 5: Solve for x
   x = 421,188,020,100/423,642
6. Step 6: Final answer
   x = 994,207.42