Finding the Third Proportional to 259,987 and 399,441.75

Step by Step Solution

1. Step 1: Write the proportion equation
   259,987 : 399,441.75 = 399,441.75 : x
2. Step 2: Convert to fraction form
   259,987/399,441.75 = 399,441.75/x
3. Step 3: Cross multiply
   259,987x = 399,441.75 × 399,441.75
4. Step 4: Simplify right side
   259,987x = 159,553,711,643.06
5. Step 5: Solve for x
   x = 159,553,711,643.06/259,987
6. Step 6: Final answer
   x = 613,698.81