Question

the average age of 8 students is 12 year .Of them the age of one student is 19 year.what is avarage age of 7 student?
PLEASE EXPLAIN THE ANSWER ​

Answer 1

$\underline{\underline{\mathbf{\huge{Question}}}}$


The average age of 8 students is 12 year .Of them the age of one student is 19 year.what is avarage age of 7 student?


$\underline{\underline{\mathbf{\huge{Answer}}}}$


Total Students=8

Average Age=12 years

Let Actual sum of Age of all Student

=$x_1+x_2+x_3+x_4...+x_8$

We know

$\boxed{\mathtt{Average=\frac{Sum\:of\:all\:Terms}{Total\:terms}}}$

Then

$\boxed{\mathtt{\frac{x_1+x_2+x_3+x_4...+x_8}{8}=12}}$

$\boxed{\mathtt{x_1+x_2+x_3+x_4...+x_8=12\times8}}$

$\boxed{\mathtt{x_1+x_2+x_3+x_4...+x_8=96}}$

Means Sum of Total 8 student Age=96 years.

Given Age of a student=19 kg

Let Age of x1=19 kg

Then Sum of 7 others Age=96-19

=77 years

Means

$x_2+x_3+x_4...+x_8=77$

Now Total Student=7

Sum of There Age=77

$\boxed{\mathtt{Average=\frac{77}{7}}}$

$\boxed{\mathtt{Average=11\:years}}$

$\boxed{\mathbf{\huge{Average\:age=11\:years}}}$

Answer 2

Solution:-

Given:-

Number of Student= 8

Average Age of 8 Student= 12

Hence,

Average Age = Sum of Age of 8 Student/ No. of Student.

=> 12 = Sum of Age of 8 Student/8

=> 12×8 = Sum of Age of 8 Student

=> Sum of Age of 8 Student= 96 years.

Age of One Student is 19 years.

Subtracting age of 1 Student from sum of age of 8 Student.

=> 96 - 19

=> 77.

Now,

Average Age of 7 Student= Sum of Age of Students/ No. of Student

=> Average Age= 77/7

=> Average Age = 11.

Hence,

Average Age of 7 Student is 11.