Question
Given $X \sim B (n, p)$. If $n=10$ and $p=0.4$, find $E ( X )$ and var. (X).

Answer

Given, n = 10, p = 0.4
q = 1 – p = 1 – 0.4 = 0.6
Now, E(X) = np = 10 x 0.4 = 4 
Var(X) = npq = 10 x 0.4 x 0.6 = 2.4

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

A car is moving in such a way that the distance it covers, is given by the equation $s = 4t^2 + 3t,$ where s is in meters and t is in seconds. What would be the velocity and the acceleration of the car at time $t = 20$ seconds?
If $\vec{\text{a}}\text{ and }\vec{\text{b}}$ denote the position vectors of points A and B respectively and C is a point on AB such that 3AC = 2AB, then write the position vector of C.
Find the angle between the lines $\vec{\text{r}}=\big(2\hat{\text{i}}-5\hat{\text{j}}+\hat{\text{k}}\big)+\lambda\big(3\hat{\text{i}}+2\hat{\text{j}}+6\hat{\text{k}}\big)$ and $\vec{\text{r}}=7\hat{\text{i}}-6\hat{\text{k}}+\mu\big(\hat{\text{i}}+2\hat{\text{j}}+2\hat{\text{k}}\big).$
Evaluate:
$\int \frac{3}{\sqrt{7 x-2}-\sqrt{7 x-5}} \cdot d x$
Determine the order and degree of the following differential equations. state also whether they are linear or non linear.
$5\frac{\text{d}^2\text{y}}{\text{dx}^2}=\Big\{1+\Big(\frac{\text{dy}}{\text{dx}}\Big)^2\Big\}^{\frac{3}{2}}$
Evaluate the following integrals:
$\int\cot^{-1}\Big(\frac{\sin2\text{x}}{1-\cos2\text{x}}\Big)\text{dx}$
If $f(x)=x^2-2 x-3$ then find $f(A)$ when $A=\left[\begin{array}{ll}1 & 2 \\ 2 & 1\end{array}\right]$
Differentiate $\sin ^{-1}\left(\frac{2 x}{1+x^2}\right)$ w.r.t $\cos ^{-1}\left(\frac{1-x^2}{1+x^2}\right)$
Which of the following functions from $A$ to $B$ are one-one and onto?
$f_3=\{(a, x),(b, x),(c, z),(d, z)\} ; A=\{a, b, c, d,\}, B=\{x, y, z\}$
Evaluate the following : $\int \frac{1}{\sqrt{3 x+1}-\sqrt{3 x-5}} \cdot d x$