Finding the Third Proportional to 399,311 and 872,311.50

Step by Step Solution

1. Step 1: Write the proportion equation
   399,311 : 872,311.50 = 872,311.50 : x
2. Step 2: Convert to fraction form
   399,311/872,311.50 = 872,311.50/x
3. Step 3: Cross multiply
   399,311x = 872,311.50 × 872,311.50
4. Step 4: Simplify right side
   399,311x = 760,927,353,032.25
5. Step 5: Solve for x
   x = 760,927,353,032.25/399,311
6. Step 6: Final answer
   x = 1,905,600.78