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Recent questions tagged p211

Find the mean and variance for the following probability density functions $f(x) = \left\{ \begin{array}{l l} xe^{-x}, & \quad \text{if $x$$>$0}\\ 0, & \quad \text{otherwise} \end{array} \right.$

asked Apr 20, 2013 by poojasapani_1

1 answer

Find the mean and variance for the following probability density functions $f(x) = \left\{ \begin{array}{l l} \alpha e^{-\alpha x} ,& \quad \text{if $x$$>$$0$}\\ 0 ,& \quad \text{otherwise} \end{array} \right.$

asked Apr 20, 2013 by poojasapani_1

1 answer

Find the mean and variance for the following probability density functions $f(x) = \left\{ \begin{array}{l l} \frac {1}{24} ,& \quad \text{-12$\leq$$ x$$\leq $$12$}\\ 0, & \quad \text{otherwise} \end{array} \right.$

asked Apr 20, 2013 by poojasapani_1

1 answer

The probability distribution of a random variable $x$ is given below: \[\] $\begin{array} {llllllll} \textbf{X:}& 0& 1& 2& 3 \\ \textbf{P(X=x):}& 0.1& 0.3 &0.5& 0.1& \end{array}$\[\] If $Y=X^{2}+2X$ find the mean and variance of $Y$.

asked Apr 20, 2013 by poojasapani_1

1 answer

In a gambling game a man wins Rs.$10 $ if he gets all heads or all tails and loses Rs.$5$ if he gets $1$ or $2$ heads when $3$ coins are tossed once. Find his expectation of gain.

asked Apr 20, 2013 by poojasapani_1

1 answer

Two cards are drawn with replacement from a well shuffled deck of $52$ cards. Find the mean and variance for the number of aces.

asked Apr 20, 2013 by poojasapani_1

1 answer

In an entrance examination a student has to answer all the $120$ questions. Each question has four options and only one option is correct. A student gets $1$ mark for a correct answer and loses half mark for a wrong answer. What is the expectation of the mark scored by a student if he chooses the answer to each question at random?

asked Apr 20, 2013 by poojasapani_1

1 answer

Find the expected value of the number on a die when thrown.

asked Apr 20, 2013 by poojasapani_1

1 answer

A die is tossed twice. A success is getting as odd number on a toss. Find the mean and the variance of the probability distribution of the number of successes.

asked Apr 20, 2013 by poojasapani_1

1 answer

Find a point on the curve $y = (x – 2)^2 $ at which the tangent is parallel to the chord joining the points $(2, 0)$ and $(4, 4)$.

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find points at which the tangent to the curve $y = x^3 - 3x^2 - 9x + 7$ is parallel to the $x$ - axis.

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the normal to the curve $ x = 1 - a \sin\theta, y = b \cos^2\theta$ at $ \theta = \Large {\frac{\pi}{2}}$

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the normal to the curve $ x = a \cos^3\theta, \: y = a \sin^3\theta$ at $ \theta =\Large {\frac{\pi}{4}}$.

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the tangent to the curve $y = x^3 - 3x + 2$ at the point whose $x$ - coordinate is $3$.

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the tangent to curve $ y = x^3 - x + 1$ at the point whose $x$ - coordinate is $2$.

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the tangent to the curve $\normalsize y =\large { \frac{x-1}{x-2},} \normalsize x \neq 2\; at\;x = 10$

asked Nov 23, 2012 by thanvigandhi_1

1 answer

Find the slope of the tangent to the curve $y = 3x^4 – 4x \; at\; x = 4.$

asked Nov 23, 2012 by thanvigandhi_1

1 answer

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