Question

if in a class there are 20 students the average increased by 3 years if a student in a class whose age is 15 years is replaced by a teacher what is the age of teacher?​

Answer 1

Answer:

Let the age of each student be x years

Then, the age of teacher will be (x+20) years

Mean age =

4

(x+20)+3x

20=

4

(4x+20)

⇒x=15

Hence, age of the teacher =35 years

hope it helps you

Answer 2

Answer:

(x+20) +3x/4

20=4x+20/4

x=15

hence age of the teacher is35 years