Question

The average age of a class is 20 years.If 16 students of average age 20 yrs and 6 months join the class the average will be increased by 2 months.find the strength of the class?

Answer 1

Solution:
let the initial number of students = X
Therefore , total number of Students = X + 16
According to problem ,
Average age of 16 students = 20 years and six months = 20.5 years
Average age of initial students = 20 years
and Average age of Total Students = 20 years and  2 months = 20.16 years
Hence ,
16*20.5 + X*20= (16+X)*20.16
 328+ 20X = 322.66 + 20.16X
328 - 322.66 = 20.16X - 20X
 5.33 = .16X
OR X = 5.33/.16
OR X = 33.33
hence X= 33 (ignoring .33)

therefore total number of students = X+16
                                                 =33+16
                                                 = 49

hope this helps you!!