There are 20 students with an average height of 105cm in a class. then 10 students with an average height of 120cm join the class. what will be the average height of the class row?
Answers
=2100 cm.
total heights of new group of students of class= 10× 120 cm= 1200 cm.
total students=20 + 10= 30.
total heights of students=2100 + 1200= 3,300 cm.
New average height of students=their total heights/total no.of students
= 3,300/ 30cm
= 110 cm.
Given:
The average height of 20 students=105 cm
To find:
The average height of the class
Solution:
The average height of the class is 110 cm.
We can find the height by taking the given steps-
We know that the average is obtained by dividing the sum of the heights of all students by the number of students in the class.
We are given that the average height of 20 students=105 cm
Let the sum of heights of these 20 students be H.
So, the average height of 20 students=Sum of the heights of 20 students/20
105=H/20
105×20=H
2100 cm=H
Now, 10 students with an average height of 120 cm join the class.
So, the total number of students in the class= Original number of students+ students joined
=20+10=30 students
Sum of the height of 10 students/10=120
Sum of the height of 10 students=120×10
Sum of the height of 10 students=1200
The sum of the height of all the students=Sum of the height of 20 old students+sum of heights of 10 new students
=2100+1200
=3300 cm
The average height of the class=Sum of the height of all students/Total number of students
On putting the values,
The average height of the class=3300/30
=110 cm
Therefore, the average height of the class is 110 cm.