Question

- The average age of 30 students in a class is 12
years. The average age of a group of 5 of the
students is 10 years and that of another group
of 5 of them is 14 years. The average age of
the remaining students is
​

Answer 1

Step-by-step explanation:

Sum of the average age of 30 students =

$30 \times 12 = 360$

Sum of the group of 5 students average age =

$5 \times 10 = 50$

Sum of average age of next 5 students group=

$5 \times 14 = 70$

How many students left from 30 after these two groups=

$30 - 5 + 5 = 30 - 10 \\ 30 - 10 = 20$

$sum \: of \: age \: of \: 10 \: students = 70 + 50 = 120years$

We know that sum of age of 30 students is 360 years we also know that sum of age of first two groups students is 120 years so sum of age of rest 20 students is

$360 - 120 = 240 \: years$

Now we have to find the average of these 20 students so we will divide 240 years with 20 to find the answer

$average \: of \: 20 \: students = 240 \div 20 = 12years \: is \: average \: of \: this \: group$