Finding the Third Proportional to 421,536 and 643,008

Step by Step Solution

1. Step 1: Write the proportion equation
   421,536 : 643,008 = 643,008 : x
2. Step 2: Convert to fraction form
   421,536/643,008 = 643,008/x
3. Step 3: Cross multiply
   421,536x = 643,008 × 643,008
4. Step 4: Simplify right side
   421,536x = 413,459,288,064
5. Step 5: Solve for x
   x = 413,459,288,064/421,536
6. Step 6: Final answer
   x = 980,839.81