6. Mean and Variance of continuous
random variable
The expectation of a continuous random variable X with probability density
function f is the number
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x
x
xf
X d
)
(
]
[
E
2
2
]
[
E
]
[
E
)
(
Var X
X
X
7. Questions
Q:1 A random variable X is of continuous type with p.d.f.
f(x)=2x, 0<x<1,
=0, elsewhere
Find its mean and variance
Q:2 Find the mean and Variance of the random variable X having the p.d.f
f(x)=2(1-x) , 0<x<1
=0, elsewhere
Find its mean and variance
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8. HOME ASSIGNMENT
Q:3 A random variable X has a density function given by
f(x)=4(𝑥 − 𝑥3
) 0<x<1,
=0, elsewhere
Find its mean and variance
Q:4 Given the following function
f(x)=
2
27
(4𝑥 − 2𝑥3) 0<x<2
=0, elsewhere
compute its mean .
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9. HOME ASSIGNMENT
Q:5 A random variable X has a density function given by
f(x)=𝑥3
(1 − 𝑥 ) 0<x<1,
=0, elsewhere
Q:6 Given the following function
f(x)=
3
4
𝑥(2 − 𝑥) 0≤x ≤ 2
=0, elsewhere
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11. References
Probability and Statistics for Engineers and Scientists by Ronald E.
Walpole, Raymond H. Myers, Sharon L. Myers and Keying E. Ye, Pearson;
9th Edition (January 6, 2011). ISBN-10: 0321629116 2
Walpole, P.E., Myers R.H., Myers S.L. (1998), “Probability and Statistics for
Engineers and Scientists”, 7th Ed. Prentice Hall.
Introduction to Statistical Theory Part 1,Prof Sher Muhammad Chaudhry
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