The average age of 3 friends is 23. Even if the age of the 4th friend is added, the average remains 23. What is the age of the 4th friend?

23 years

22 years

33 years

None of these

Sum of the ages of 3 friends =3×23= 69 years

Sum of the ages of 4 friends =4×23= 92 years

∴ Age of 4th friend = 92 years - 69 years = 23 years.