spring2008stat201exam1-version3KEY

spring2008stat201exam1-version3KEY - Stat 201 Exam 1 Spring...

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Stat 201 Exam 1 Spring 2008 Version 3 Answer Key Page 1 of 13 1. Suppose a sample of students is asked, “How long did you sleep last night?” The results are graphically displayed as follows: (a) How many total people are represented in the data displayed? Circle the best answer: [2 pts] (i) 9 (ii) 8 (iii) 7 (iv) 6 (v) 42 (vi) 25 (the total height of the bars) (b) How many variables are represented? Circle the best answer: [3 pts] (i) Nine. (ii) Eight. (iii) Seven. (iv) Six. (v) Forty two. (vi) Twenty five. (vii) One (time of sleep). (viii) One (frequency). (ix) Two. [exercise 1 continues on next page]
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Stat 201 Exam 1 Spring 2008 Version 3 Answer Key Page 2 of 13 Here is the same display from above, but with one part shaded: (c) The shaded part of the display on this page represents which of the following [choose the best answer]: [3 pts] (i) Four people, who slept a total of 7 hours combined. (ii) Four people, who slept exactly 7 hours each. (iii) Four people, who slept between 3 and 7 hours each. (iv) Seven people, who slept a total of 4 hours combined. (v) Seven people, who slept exactly 4 hours each. (vi) Seven people, who slept between 3.5 and 4.5 hours each. (this is just like question #2c of lab 1) (vii) One person, with a data value given by the x y coordinate pair (4, 7) (viii) One person, who slept 7 hours. (ix) One person, who slept 4 hours.
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Stat 201 Exam 1 Spring 2008 Version 3 Answer Key Page 3 of 13 2. Suppose a large random sample of high-school students is given a 10-point exam to measure mathematical understanding. The histogram of the resulting dataset is shown: (a) State the modality of the distribution: [1 pt] Bi-modal (or ‘two’ or ‘double’, etc.) (b) Describe the skewness (or symmetry) of the distribution: [1 pt] Skewed, to the left (or ‘…to the low side’, or ‘…to the negative , or any similar terminology) (c) Say whether there appear to be any suspected outliers (and if so, how many , and where ): [2 pts] There are FIFTEEN outliers, ‘on the low side’ (or ‘…on the left’ or ‘…at 0.5’ or ‘….between 0.3 and 0.6…’) (note that the bar in question represents fifteen students) (d) There are some data values that are clear outliers in the plot. If these outlying values were removed , the effect on mean and standard deviation would be which one of the following: [3 pts] (i) Mean and standard deviation would both increase. (ii)
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This note was uploaded on 02/01/2009 for the course STAT 36-201 taught by Professor Gordon during the Fall '08 term at Carnegie Mellon.

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spring2008stat201exam1-version3KEY - Stat 201 Exam 1 Spring...

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