2018FA-MATH-1051H.hbrettpickering.2018-Assignment2.pdf

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Heather Brett-Pickering 2018FA-MATH-1051H Assignment 2018-Assignment2 due 09/24/2018 at 11:59pm EDT 1. (1 point) A choral conductor has 1475 singers in her choir, some of them are professional singers. The conductor wants to estimate what percentage of singers are professional, but can’t ask all 1475, so she instead asks 700 singers in front and finds 28 who are professionals. (a) Identify the parameter A. percentage of entire singers who are professional B. range of values in which 95% values fall C. 28 D. None of the above. (b) Identify the sample. A. 28/1475 B. singers who were asked C. 700 D. None of the above. (c) Identify the statistic. A. entire choir members B. 28/700 C. 1475 D. None of the above. (d) What specific type of bias does this scenario demon- strate? A. Voluntary response sampling B. It is representative of the population. C. Convenience Sampling D. None of the above. Correct Answers: A B B C 2. (1 point) A poll is sent out to 190 employees at a hostpital. Only 31% bother to fill them out and return them. This an example of Correct Answers: A 3. (1 point) A boxplot for a set of data is given below. Find the five-number summary Find the minimum: Find Q 1 : Find the median: Find Q 3 : Find the maximum: Correct Answers: 2 3 6 14 16 4. (1 point) In a statistics class with 136 students, the profes- sor records how much money each student has in their posses- sion during the first class of the semester. The histogram below is of the data collected. ( Click on the image for a larger view. ) possession is possession is closest to A. 40 B. 50 C. 60 D. 70 1
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(c) The histogram A. is asymmetric. B. has an outlier. C. is skewed right. D. all of the above. Correct Answers: D C D 5. (1 point) Identify each quantity as a parameter or statistic Write ”pa- rameter” or ”statistic”. (without quotations) (a) μ answer: (b) σ answer: (c) s answer: (d) x answer: Correct Answers: PARAMETER PARAMETER STATISTIC STATISTIC 6. (1 point) The times (in seconds) between fifteen consecutive eruptions of a geyser were as follows: 854, 884, 904, 921, 869, 888, 847, 911, 856, 934, 861, 897, 929, 911, 830 By entering the data into R, find the following (giving an- swers to two decimal places): Part a) The sample mean is (sec). Part b) The sample variance is (sec 2 ). Part c) The sample median is (sec). Part d) The sample IQR is (sec). Part e) Which of the following is a boxplot of the data? [?/A/B/C/D] 2
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A B C D (Click on a graph to enlarge it.) Solution: Suppose you have entered the data in R as follows: x <- c( 854, 884, 904, 921, 869, 888, 847, 911, 856, 934, 861, 897, 929, 911, 830 ) 3
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Then the sample mean, sample variance, sample median, and sample IQR are obtained as follows: mean(x) var(x) median(x) IQR(x) You can obtain a boxplot by typing boxplot( x, ylab = "Times between eruptions (in sec)", id.method="y")
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