Question

the average age of a class of 20 students is 15 years and the average age of another class of 30 students is 20 years .find the average age of students into classes​

Answer 1

Let’s say the first class is X.

Avg(X)= x/20=15

X=300

Let’s say the second class is Y.

Avg(Y)= Y/30=20

Y=600

X+Y=900

AVG(X+Y)=900/(20+30)=900/50=18

The average of both classes is 18.