# stats practice ques....

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## stats practice ques....

 Consider a random variable x that follows a normal distribution N(u,Sigma^2) find an expression for Expectation(X^2) Akshay Jain Masters in Economics Delhi School of Economics 2013-15
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## Re: stats practice ques....

 This post was updated on . E(X^2) = Sigma^2 - u^2 Sorry, it should be- E(X^2) = SIgma^2 + u^2
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## Re: stats practice ques....

 Hi Akshay, for regression and correlation in ISI, which book should I refer to?
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## Re: stats practice ques....

 read basic econometrix by gujarati word by word....cant find any better book dan dis 1 Also u can have a look at Introduction to econometrix by stock and watson...u can find PDF's of both Akshay Jain Masters in Economics Delhi School of Economics 2013-15
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## Re: stats practice ques....

 In reply to this post by Arushi1 also in the same question find Expectation(X^3) Akshay Jain Masters in Economics Delhi School of Economics 2013-15
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## Re: stats practice ques....

 In reply to this post by Akshay Jain How to find E(X^2)...i didnt get it
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## Re: stats practice ques....

 E(X^2)-(E(X))^2=sigma^2 E(X^2)=sigma^2+(E(X))^2 E(X^2)=sigma^2+(u)^2 Akshay Jain Masters in Economics Delhi School of Economics 2013-15
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## Re: stats practice ques....

 This post was updated on . CONTENTS DELETED The author has deleted this message. “Operator! Give me the number for 911!”
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## Re: stats practice ques....

 CONTENTS DELETED The author has deleted this message.
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## Re: stats practice ques....

 khiladi, your answer is right. i mixed up the formula -_- “Operator! Give me the number for 911!”
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## Re: stats practice ques....

 In reply to this post by Akshay Jain Akshay...how to find E(X^3)
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## Re: stats practice ques....

 Find the 3rd moment of X about mean ..this will b zero bcoz normal distribution is symmetric (odd moments of symmetric distributions about mean is 0) so E(X-u)^3 =0 E(X^3)= u^3 +3*u*E(X^2)-3*u^2*E(X) put the values of E(X^2) and E(X) nd get the ans Akshay Jain Masters in Economics Delhi School of Economics 2013-15