Practice Set 3

# Practice Set 3 - Multiple choice set 3 INFO: practice...

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Multiple choice set 3 INFO: practice multiple choice questions related to chapters 6, 7; hypothesis testing and assignments 4, 5. The ﬁrst part consists of 10 multiple choice questions, in the second part you have to answer TRUE or FALSE . Q 1. In a random sample of 1000 homes in a certain city, it is found that 228 are heated by oil. Find a 99% conﬁdence interval for the proportion of homes from this city that are heated by oil. (a) [0.202,0.254] (b) [0.197,0.259] (c) [0.194,0.262] (d) [0.185,0.247] (e) none of the preceding Solution to Q1: b p ± z . 005 r b p (1 - b p ) n = 228 1000 ± 2 . 576 r 228 / 1000 (1 - 228 / 1000) 1000 So [0 . 194 , 0 . 262]. Q 2. In Canada, foreign undergraduate students account for 7% (data from StatCanada for 2003/2004). A politician wants to prove that this percentage declined in 2008. To do this, the politician chooses randomly 100 students, and only 4 of them were non-Canadian (international). The P -value for the test H 0 : p = 0 . 07 vs. H A : p < 0 . 07 is (choose the closest one): (a) 0.84 (b) 0.16 (c) 0.04 (d) 0.07 (e) none of the preceding The following MINITAB output will be helpful: Binomial with n = 100 and p = 0.07 x P( X = x ) 0 0.000705 1 0.005308 2 0.019776 3 0.048624 4 0.088752 5 0.128261 Solution to Q2: Model: X - # of international students; Under H 0 , X B (100 , 0 . 07). P -value: P ( X 4) = 0 . 16. Not enough evidence against H 0 . It is really the case: the percentage of international undergraduate students remains the same 7%. Source: StatCanada. Q 3. Assume that we have 25 observations from a normal population with the known variance 1. If the sample mean is ¯ y = 20, the appropriate 95% conﬁdence interval is (a) [19 . 000 , 21 . 000] (b) [19 . 587 , 20 . 413] (c) [19 . 608 , 20 . 391] (d) [21 . 014 , 22 . 035] (e) none of the preceding. Solution to Q3:

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20 ± 1 . 96 / 5, where 1 . 96 = z 0 . 025 . Note: if you use (incorrectly) percentiles of t 24 , you end up with (b). Q 4. A zoologists measured tail length in 81 individuals, all in the one year age group of Peromyscus . The sample mean length was 60.43 mm, the sample standard deviation was was 3.06 mm. The appropriate 95% conﬁdence interval for the population mean is
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## This note was uploaded on 12/22/2011 for the course STATISTICS STAT 3502 taught by Professor Alyaothman during the Spring '09 term at University of Ottawa.

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Practice Set 3 - Multiple choice set 3 INFO: practice...

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