JEE Main On 8 April 2017 Question 23
Question: The mean age of 25 teaches in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place. If now the mean age of the teachers in this school is 39 years, then the age (in years) of the newly appointed teachers is: [JEE Online 08-04-2017]
Options:
A) 35
B) 40
C) 25
D) 30
Show Answer
Answer:
Correct Answer: A
Solution:
$ \frac{x _1+x _2+…+x _{25}}{25}=\overline{x}=40 $
$ x _1+x _2+…+x _{25}=1000 $
$ x _2+x _2+…+x _{25}=60+A=\overline{x}\times 25 $
$ 1000-60+A=39\times 25=975 $
$ A=975-940=35 $
