Finding the Third Proportional to 399,115.50 and 631,870.50

Step by Step Solution

1. Step 1: Write the proportion equation
   399,115.50 : 631,870.50 = 631,870.50 : x
2. Step 2: Convert to fraction form
   399,115.50/631,870.50 = 631,870.50/x
3. Step 3: Cross multiply
   399,115.50x = 631,870.50 × 631,870.50
4. Step 4: Simplify right side
   399,115.50x = 399,260,328,770.25
5. Step 5: Solve for x
   x = 399,260,328,770.25/399,115.50
6. Step 6: Final answer
   x = 1,000,362.87