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Unformatted text preview: 7.5 #4 a. since the sample mean is below 30 we can not say anything about x distribution of sample means. b. Since the x distribution is given to be normal, the x distribution also will be normal even though the sample size is much less than 30. The mean is 72 2 16 8 = The x distribution is normal with the mean of 72 and standard deviation of 2 x μ = μ =72 = = 16 / 8 \ x σ 2 z= 2 72 73 2 72 68 ≤ ≤ x = 2 ≤ ≤ z 0.5 P ) 5 . 2 ( ) 73 68 ( ≤ ≤ = ≤ ≤ z P x =P (z ) 2 ( ) 5 . ≤ ≤ z P 0.51990.0228=0.4971 #6 a. 68 = = μ μ x / 3 = x σ = 18 0.71 z 8414 . 0793 . 9207 . ) 41 . 1 ( ) 41 . 1 ( 41 . 1 41 . 1 ( ) 69 67 ( 41 . 1 41 . 1 71 . 68 69 71 . 68 67 = = ≤ ≤ = ≤ ≤ = ≤ = ≤ ≤ = ≤ ≤ Pz z P z P P z z b. 1 9 / 3 68 = = = = x x σ μ μ z 6826 . 1587 . 8413 . ) 00 . 1 ( ) 00 . 1 ( 00 . 1 00 . 1 ( ) 69 67 ( 00 . 1 00 . 1 1 68 69 1 68 67 = = ≤ ≤ = ≤ ≤ = ≤ = ≤ ≤ = ≤ ≤ Pz z P z P P z z c. no, it is not higher, because you only have a sample of 9 in part b and a all the population in part a. #10 a. It is normal probability distribution, yes it is approximately normal, the mean is 16 and sd is approximately 2 37 . 30 / 2 16 = = = = x x σ μ μ z 4965 . 5000 . 9965 . ) ( ) 70 . 2 ( ) 70 . 2 ( 16 16 ( 70 . 2 37 . 16 17 37 . 16 16 = = ≤ ≤ = ≤ ≤ = ≤ = ≤ ≤ = ≤ ≤ Pz z P z P P z z c....
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This note was uploaded on 08/05/2008 for the course MM 207 taught by Professor Hill during the Spring '08 term at Kaplan University.
 Spring '08
 hill

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