Finding the Third Proportional to 259,221 and 400,315.50

Step by Step Solution

1. Step 1: Write the proportion equation
   259,221 : 400,315.50 = 400,315.50 : x
2. Step 2: Convert to fraction form
   259,221/400,315.50 = 400,315.50/x
3. Step 3: Cross multiply
   259,221x = 400,315.50 × 400,315.50
4. Step 4: Simplify right side
   259,221x = 160,252,499,540.25
5. Step 5: Solve for x
   x = 160,252,499,540.25/259,221
6. Step 6: Final answer
   x = 618,208.01