Question

Mean of ages of 20students is 10years. 5students with mean age of 12 years leave the class. Mean of ages of remaining students will be-• 4• 5
.66• 6.25• 9.33

Answer 1

Mean age of remaining students is 9.33 years.

Step-by-step explanation:

We are given that Mean of ages of 20 students is 10 years.

Also, 5 students with mean age of 12 years leave the class and we have to find the Mean age of remaining students.

As we know that Mean formula, $\bar X = \frac{\sum X}{n}$

where, = Total Sum of n observation

                  n = Number of observation

So, Total Sum of n observation ($\sum X$) =  

                          $\text{Mean} (\bar X) \times \text{Number of observation} (n)$  

So, Total sum of ages of 20 students =  $10 \times 20$ = 200

Also, Total sum of ages of 5 students who leave the class = $12 \times 5$ = 60

Now, Mean age of remaining 15 students =

                              $\frac{\text{Total sum of ages of remaining 15 students}}{15}$  

Here, Total sum of ages of remaining 15 students = 200 - 60 = 140

          Number of remaining students = 15

Hence, Mean age of remaining students = $\frac{140}{15}$ = 9.33 years.

Answer 2

Answer:

9.33 years

Step-by-step explanation:

Mean age of remaining students is 9.33 years.

Step-by-step explanation:

We are given that Mean of ages of 20 students is 10 years.

Also, 5 students with mean age of 12 years leave the class and we have to find the Mean age of remaining students.

As we know that Mean formula,  

where, = Total Sum of n observation

                 n = Number of observation

So, Total Sum of n observation () =  

                           

So, Total sum of ages of 20 students =   = 200

Also, Total sum of ages of 5 students who leave the class =  = 60

Now, Mean age of remaining 15 students =

                               

Here, Total sum of ages of remaining 15 students = 200 - 60 = 140

         Number of remaining students = 15

Hence, Mean age of remaining students =  = 9.33 years.