The average age of 40 students of a class is 16 years. After admission of 10 new students to the class, the average becomes 15 years. If the average age of 5 of the new students is 11 years, then the average age (in years) of the remaining 5 new student is :

11

Sum of ages of 40 students = 40 x 16 = 640

Sum of ages of 50 students = 50 x 15 = 750

Sum of ages of 10 new students = 750 - 640 = 110

Sum of ages of 5 students among 10 new = 5 x 11 = 55

Sum of ages of remaining 5 students = 110 - 55 = 55

Average of 5 new students = \(\frac{55}{5}\) = 11