The mean age of 25 teachers in a school is 40 years. A teacher re… - Vidyadip

MCQ

The mean age of $25$ teachers 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 the mean age of the teachers in this school now is $39$ years, then the age (in years) of the newly appointed teacher is..........

A
$40$
✓
$35$
C
$48$
D
$56$

✓

Answer

Correct option: B.

$35$

b
$\frac{\sum x _{ i }}{25}=40 \& \frac{\sum x _{ i }-60+ N }{25}=39$

Let age of newly appointed teacher is $N$

$\Rightarrow 1000-60+ N =975$

$\Rightarrow N =35$ years

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