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Chebyshev’s inequality, (see Exercise 44, Chapter 3), is
Chapter 5, Problem 51E(choose chapter or problem)
Chebyshev’s inequality, (see Exercise 44, Chapter 3), is valid for continuous as well as discrete distributions. It states that for any number k satisfying k ? 1,P(|X – ? ?k?) ?1/k2 (see Exercise 44 in Chapter 3 for an interpretation). Obtain this probability in the case of a normal distribution for , 2, and 3, and compare to the upper bound. Reference exercise 44 A result called ?Chebyshev’s inequality ?states that for any probability distribution of an rv ?X ?and any number ?k ?that is at least 1,? P?( | ?X ?- µ | k ?) ? 1/?k?2 . In words, the probability that the value of ?X ?lies at least ?k ?standard deviations from its mean is at most 1/?k?2. a.? hat is the value of the upper bound for k = 2? K + 3? K = 4? K= 5? K = 10? b.? ?Compute µ and ? for the distribution of Exercise 13. Then evaluate P(|X - µ| ? k?) for the values of ?k ?given in part (a). What does this suggest about the upper bound relative to the corresponding probability? c.? ?Let ?X ?have possible values -1, 0, and 1, with probabilities 1/18, 8/9 and 1/8 , respectively. What is P(|X - µ|? 3?), and how does it compare to the corresponding bound? d.? ?Give a distribution for which P(|X - µ|? 5?) = .04.
Questions & Answers
QUESTION:
Chebyshev’s inequality, (see Exercise 44, Chapter 3), is valid for continuous as well as discrete distributions. It states that for any number k satisfying k ? 1,P(|X – ? ?k?) ?1/k2 (see Exercise 44 in Chapter 3 for an interpretation). Obtain this probability in the case of a normal distribution for , 2, and 3, and compare to the upper bound. Reference exercise 44 A result called ?Chebyshev’s inequality ?states that for any probability distribution of an rv ?X ?and any number ?k ?that is at least 1,? P?( | ?X ?- µ | k ?) ? 1/?k?2 . In words, the probability that the value of ?X ?lies at least ?k ?standard deviations from its mean is at most 1/?k?2. a.? hat is the value of the upper bound for k = 2? K + 3? K = 4? K= 5? K = 10? b.? ?Compute µ and ? for the distribution of Exercise 13. Then evaluate P(|X - µ| ? k?) for the values of ?k ?given in part (a). What does this suggest about the upper bound relative to the corresponding probability? c.? ?Let ?X ?have possible values -1, 0, and 1, with probabilities 1/18, 8/9 and 1/8 , respectively. What is P(|X - µ|? 3?), and how does it compare to the corresponding bound? d.? ?Give a distribution for which P(|X - µ|? 5?) = .04.
ANSWER:Answer : Step 1 of 3 : Let the Chebyshev’s inequality be P( X k| ) | 12 k We have to find the probability values for normal distribution for k = 1, 2 and 3 By normal distribution, For k = 1 P( | |) 1 = 1 - P(- < (x - )< ) k2 = 1 - P(-1< (x - )<1) 2 1 = 1 - ( (z 1) - (z-1) ) Where, (z 1) = 0.8413 ( from the standard normal table) (z - 1) = 0.1587 ( from the standard normal table) Therefore, P( | |) = 1 - ( 0.8413 - 0.1587 ) = 1 - 0.6826 = 0.3174 Hence the equation satisfies