Finding the Third Proportional to 128,978 and 280,981

Step by Step Solution

1. Step 1: Write the proportion equation
   128,978 : 280,981 = 280,981 : x
2. Step 2: Convert to fraction form
   128,978/280,981 = 280,981/x
3. Step 3: Cross multiply
   128,978x = 280,981 × 280,981
4. Step 4: Simplify right side
   128,978x = 78,950,322,361
5. Step 5: Solve for x
   x = 78,950,322,361/128,978
6. Step 6: Final answer
   x = 612,122.40