Question

The average of 12 students is decreased by 9 months when a student whose age is 18 years is replaced by a new student. what is the age if new student​

Answer 1

Answer:

find all the structural isomers of dichloroderivative of cyclopentane (draw)

Step-by-step explanation:

The average of 12 students is decreased by 9 months when a student whose age is 18 years is replaced by a new student. what is the age if new student

give thumps.to this answer

Answer 2

Answer:

And is 9 years

Step-by-step explanation:

Let x be the avg of 12 students then the sum of all their ages is 12×x from this subtract the boy with age 18 and added by some other whose age is y

Then new avg is (12x-18+y)/12

Which is given that the new avg is as per sum

x-9/12 since 9 months is equal to 9/12 years.

So from the above

x-18/12+y/12=x-3/4

x get cancelled

so y/12=3/2-3/4=y/12=3/4

Y=9 on solving

Hope you understand