Finding the Third Proportional to 259,287 and 423,388.50

Step by Step Solution

1. Step 1: Write the proportion equation
   259,287 : 423,388.50 = 423,388.50 : x
2. Step 2: Convert to fraction form
   259,287/423,388.50 = 423,388.50/x
3. Step 3: Cross multiply
   259,287x = 423,388.50 × 423,388.50
4. Step 4: Simplify right side
   259,287x = 179,257,821,932.25
5. Step 5: Solve for x
   x = 179,257,821,932.25/259,287
6. Step 6: Final answer
   x = 691,349.05