Finding the Third Proportional to 260,018 and 399,488

Step by Step Solution

1. Step 1: Write the proportion equation
   260,018 : 399,488 = 399,488 : x
2. Step 2: Convert to fraction form
   260,018/399,488 = 399,488/x
3. Step 3: Cross multiply
   260,018x = 399,488 × 399,488
4. Step 4: Simplify right side
   260,018x = 159,590,662,144
5. Step 5: Solve for x
   x = 159,590,662,144/260,018
6. Step 6: Final answer
   x = 613,767.75