Finding the Third Proportional to 258,690.50 and 386,443

Step by Step Solution

1. Step 1: Write the proportion equation
   258,690.50 : 386,443 = 386,443 : x
2. Step 2: Convert to fraction form
   258,690.50/386,443 = 386,443/x
3. Step 3: Cross multiply
   258,690.50x = 386,443 × 386,443
4. Step 4: Simplify right side
   258,690.50x = 149,338,192,249
5. Step 5: Solve for x
   x = 149,338,192,249/258,690.50
6. Step 6: Final answer
   x = 577,285.18