Finding the Third Proportional to 405,678 and 636,367.50

Step by Step Solution

1. Step 1: Write the proportion equation
   405,678 : 636,367.50 = 636,367.50 : x
2. Step 2: Convert to fraction form
   405,678/636,367.50 = 636,367.50/x
3. Step 3: Cross multiply
   405,678x = 636,367.50 × 636,367.50
4. Step 4: Simplify right side
   405,678x = 404,963,595,056.25
5. Step 5: Solve for x
   x = 404,963,595,056.25/405,678
6. Step 6: Final answer
   x = 998,238.99