Question

The mean of 30 students in a class is 14 years.5 students with mean age 15 years left the class.find the mean age of the remaining students

Answer 1

mean of 30 students = 14 years
total age of 30 students =14×30=420yrs
mean of 5 students =15
total age =15×5=75 yrs
students left (age) =420-75=345
students left =30 -5=25
mean=345÷25
=13.8

Answer 2

Answer: 13.8 yrs

Explanation:

Let sum of all observations be y

Now,

Mean=sum of all observations/no. of

students

Mean=y/30

Since, Mean=14

Therefore,

14=y/30

y=14×30

y=420

5 students left with mean age of 15 yrs,

Therefore, decrease in sum of all observations = 5×15 = 75 yrs

Now,

New Mean = y-75/30-5

= 420-75/25

=345/25

=13.8 yrs