Download App

Probability — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsProbability1 Mark
MCQ
10 persons are seated around a round table. What is the probability that 4 particular persons are always seated together?
  • A
    $\frac{1}{20}$
  • B
    $\frac{4}{10}$
  • C
    $\frac{1}{21}$
  • D
    $\frac{3}{20}$
✓

Answer

  1. $\frac{1}{21}$

Solution:

10 persons can sit around a table in 9! ways.

Consider the particular four persons as one unit.

Now, the entities are 6 + 1 = 7

These 7 entities can be arranged in 6! ways.

In the entities itself they can be arranged in 4! ways.

The required number of arrangements = 6!4!

Probability $= \text{nm}​ = \frac{!6!4}{9!} ​= \frac1{21}​$

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 "M.C.Q (1 Marks)" from Probability→Probability — all question types→Maths STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

If $\vec{\text{a}},\vec{\text{b}},\vec{\text{c}}$ are any three mutualy perpendicular vectors of equal magnitude a, then $\big|\vec{\text{a}}+\vec{\text{b}}+\vec{\text{c}}\big|$ is equal to
  1. $\text{a}$
  2. $\sqrt{2}\text{a}$
  3. $\sqrt{3}\text{a}$
  4. $2\text{a}$
  5. $\text{None of these}$
→
$\int_{\,0}^{\,1000} {{e^{x - [x]}}dx} $ is
→
If $\left|\begin{array}{cc}x & 2 \\ 15 & x\end{array}\right|=\left|\begin{array}{ll}6 & 6 \\ 3 & 4\end{array}\right|$ then $x=$ _________.
→
The domain of the derivative of the function $f(x) = \left\{ \begin{array}{l}{\tan ^{ - 1}}x\;\;\;\;\;,\;|x|\; \le 1\\\frac{1}{2}(|x|\; - 1)\;,\;|x|\; > 1\end{array} \right.$ is
→
In a sphere the rate of change of volume is:

  1.  $\pi$ times the rate of change of radius.

  2.  Surface area times the rate of change of diameter.

  3.  Surface area times the rate of change of radius.

  4.  None of these.

→
${{{d^2}} \over {d{x^2}}}(2\cos x\,\cos 3x) = $
→
Choose the correct answer in each of the following:
If A and B are any two events such that P(A) + P(B) – P(A and B) = P(A), then
  1. P(B|A) = 1
  2. P(A|B) = 1
  3. P(B|A) = 0
  4. P(A|B) = 0
→
The value of a for which the function $\text{f(x)}=\begin{cases}5\text{x}-4,&\text{if }0<\text{x}\leq1\\4\text{x}^2+3\text{ax},&\text{if }<\text{x}<2\end{cases}$ is continuous at every point of its domain, is:
  1. $\frac{13}{3}$
  2. 1
  3. 0
  4. -1
→
The differential equation of the family of circles passing the origin and having center at the line $y=x$ is :
→
The adjacent sides of a rectangle with given perimeter as  $100\, cm $ and enclosing maximum area are
→