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.
Step-by-step explanation:
AVERAGE AGE OF 20 STUDENTS=15
AVERAGE AGE OF 30 STUDENTS=20
THEREFORE SUM OF Ages of 20 students=300
And sum of Ages of 30 students=600
Therefore Average age of 50 students =900/50=18