Finding the Third Proportional to 259,717 and 405,978

Step by Step Solution

1. Step 1: Write the proportion equation
   259,717 : 405,978 = 405,978 : x
2. Step 2: Convert to fraction form
   259,717/405,978 = 405,978/x
3. Step 3: Cross multiply
   259,717x = 405,978 × 405,978
4. Step 4: Simplify right side
   259,717x = 164,818,136,484
5. Step 5: Solve for x
   x = 164,818,136,484/259,717
6. Step 6: Final answer
   x = 634,606.65