MCQ
A problem in mathematics is given to 3 students whose chances of solving it are $\frac{1}{2}, \frac{1}{3}, \frac{1}{4}$. What is the probability that the problem is solved?
  • A
    $1 / 5$
  • B
    $1 / 4$
  • $3 / 4$
  • D
    $2 / 3$

Answer

Correct option: C.
$3 / 4$
(c) : Let $A, B, C$ be the respective events of solving the problem. Then, $P(A)=\frac{1}{2}, P(B)=\frac{1}{3}$ and $P(C)=\frac{1}{4}$.
Clearly $A, B, C$ are independent events and the problem is solved if atleast one student solves it.
$
\begin{array}{l}
\therefore \quad \text { Required probability }=P(A \cup B \cup C) \\
=1-P(\bar{A}) P(\bar{B}) P(\bar{C}) \\
=1-\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right)=1-\frac{1}{4}=\frac{3}{4}
\end{array}
$

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

Similar questions

Area of the region bounded by the curve $y = \tan x,$ tangent drawn to the curve at $x = \frac{\pi }{4}$ and the $x -$ axis is
Let $S=\left\{\left(\begin{array}{cc}-1 & a \\ 0 & b\end{array}\right) ; a, b \in\{1,2,3, \ldots 100\}\right\}$ and let $T_{n}=\left\{A \in S: A^{n(n+1)}=I\right\}$. Then the number of elements in $\bigcap \limits_{n=1}^{100} T_{n}$ is
Let $I(x)=\int \frac{x^2\left(x \sec ^2 x+\tan x\right)}{(x \tan x+1)^2} d x$. If $I(0)=0$ the $I$ $\left(\frac{\pi}{4}\right)$ is equal to
Define a function $f: R \rightarrow R$ by $f(x)=\left\{\begin{array}{cc}\frac{\sin x^2}{x}, & \text { for } x<0 \\ x^2+a x+b, & \text { for } x \geq 0\end{array}\right.$ Suppose $f(x)$ is differentiable of $R$. Then,
If the position vectors of the vertices of a triangle be $2i + 4j - k,$ $4i + 5j + k$ and $3i + 6j - 3k,$ then the triangle is
$\int_{\,0}^{\,\pi } {\log {{\sin }^2}x\,dx = } $
A wire of length $2$ units is cut into two parts which are bent respectively to form a square of side $= x$ units and a circle of radius $= r$ units. If the sum of the areas ofthe square and the circle so formed is minimum, then: 
The number of real solution of the equation
$\sqrt{1+\cos2\text{x}}=\sqrt2\sin^{-1}(\sin\text{x}),-\pi\leq\text{x}\leq\pi$ is:
  1. 0
  2. 1
  3. 2
  4. infinite
If P and q are the order and degree of the differention $\text{y}\frac{\text{dy}}{\text{dx}}+\text{x}^{3}\frac{\text{d}^{2}\text{y}}{\text{dx}^{3}}+\text{xy}=\cos\text{x}$ then: 
  1. $\text{p}<\text{q}$ 
  2. $\text{p}=\text{q}$
  3. $\text{p}>\text{q}$
  4. None of these. 
Area of the region bounded by the curve x = 2y + 3, the y-axis and between y = -1 and y = 1 is:
  1. $4\text{sq}\text{ units}3$
  2. $\frac{3}{2}\text{sq}\text{ units}$
  3. $6\text{sq}\text{ units}$
  4. $8\text{sq}\text{ units}$