1.

There are 20 students in a class average age of class increases by 3 months when a 23 years old student replaced by another one find the age of new student​​

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Answer:

The average age of 20 students is 12 years.

∴ Total age of 20 students =20×12=240years

It is given that, student who is 10years old left the class.

∴ Total age of 19 students =240−10=230years

An then 2 new students entered and average remain same.

∴ Total age of 21 students =21×12=252years

⇒ Total age of 2 new students who entered in the class =252−230=22years

Let X and y be the two new students.

∴ x+y=22 ------ ( 1 )

According to the question,

x−y=4 ----- ( 2 )

Now adding (1) and (2), we GET,

x=13

Putting value of x in EQUATION ( 1 ) we get,

y=9

∴ The age of YOUNGER one is 9years

Step-by-step explanation:

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