Finding the Third Proportional to 123,399 and 256,131

Step by Step Solution

1. Step 1: Write the proportion equation
   123,399 : 256,131 = 256,131 : x
2. Step 2: Convert to fraction form
   123,399/256,131 = 256,131/x
3. Step 3: Cross multiply
   123,399x = 256,131 × 256,131
4. Step 4: Simplify right side
   123,399x = 65,603,089,161
5. Step 5: Solve for x
   x = 65,603,089,161/123,399
6. Step 6: Final answer
   x = 531,633.88