The mean age of 25 teachers in a school is 40 , years. A teacher … - 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 now the mean age of the teachers in this school is $39\, years$, then the age (in years) of the newly appointed teacher is

A
$25$
B
$30$
✓
$35$
D
$40$

✓

Answer

Correct option: C.

$35$

c
$\frac{{{x_1} + {x_2} + ... + {x_{25}}}}{{25}} = \bar x = 40$

$ \Rightarrow {x_1} + {x_2} + ... + {x_{25}} = 1000$

Let $A$ be the age of new teacher.

$\therefore {x_1} + {x_2} + ... + {x_{25}} - 60 + A = 39 \times 25$

$ \Rightarrow 1000 - 60 + A = 975$

$ \Rightarrow A = 975 - 940 = 35$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "MCQ" from 13. statistics→13. statistics — all question types→MATHS STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

If $^{n}{P_4} = 24.{\,^n}{C_5},$ then the value of $n$ is

Let $S$ be the focus of the parabola $y ^2=8 x$ and let $PQ$ be the common chord of the circle $x^2+y^2-2 x-4 y=0$ and the given parabola. The area of the triangle $PQS$ is.

In the ellipse $\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1$, the equation of diameter conjugate to the diameter $y = \frac{b}{a}x$, is

The coefficient of ${x^4}$ in the expansion of the expression ${{3x} \over {(x - 2)(x + 1)}}$ is

For the ellipse $25{x^2} + 9{y^2} - 150x - 90y + 225 = 0$ the eccentricity $e = $

If $\mathop {\lim }\limits_{x \to \infty } $ $\frac{{({e^{\mu x}} + 5)}}{{({e^{100x}} + 7)}}$ exists, then sum of all possible positive integral values of $\mu $ is -

The sum of the co - efficients of all odd degree terms in the expansion of$(\text{x}+\sqrt{\text{x}^3-1})^5+(\text{x}+\sqrt{\text{x}^3-1})^5(\text{x}>1)$ is:

If the ellipse $\frac{ x ^{2}}{ a ^{2}}+\frac{ y ^{2}}{ b ^{2}}=1$ meets the line $\frac{x}{7}+\frac{y}{2 \sqrt{6}}=1$ on the $x$-axis and the line $\frac{x}{7}-\frac{y}{2 \sqrt{6}}=1$ on the $y$-axis, then the eccentricity of the ellipse is

G(1, 1, -2) is the centroid of the triangle ABC and D is the mid point of BC. If A = (-1, 1, -4) D=

If $\sec\text{x}=\text{x}+\frac{1}{4\text{x}},$ then $\sec\text{x}+\tan\text{x}=$