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Unformatted text preview: rint Name:_ _  :: 290.1755) 0 w Instructor: Dr. Jimmy Doi This is a closed book, closed notes examination. The use of a calculator is permitted. Including this
page, the exam has a total of 5 pages. There are a total of 13 questions. There are 100 points possible on this exam. Provide all answers on this exam and show all work
where appropriate. If necessary, you may use the back of these pages if you need more space. If you have any questions at all during the exam, please do not hesitate to come up and ask. Best
wishes and good luck! Read and sign the following before you submit the exam: By signing below, I understand that giving or receiving help on this exam is a
violation of academic regulations and is punishable by a grade of in the courSe
and possible further action by Cal Poly Judicial Affairs. Acts of violation include revealing (actively or passively) any information about the exam to any member of
Prof. Doi’s Stat 217 class who is currently taking or not yet taken the exam. By signing hn‘cr I pledge 11m violate academic regulations. Signature}, _ / Question 0: MAKE SURE YOUR NAME APPEARS ON THE FRONT OF THIS EXAM. Question 1: [3 points total] During many of the games of last year’s Major League Baseball World
Series, the television broadcast displayed a message at the bottom of the screen to conduct a ‘virtual
poll”. As an example, a message at the bottom of the screen would read “Should the manager withdraw
the pitcher and replace him with a reliever?”. People would then have about 3 minutes to go online
and submit their anSWer through a. website. After 3 minutes the results (in one such game) were displayed as “65% Yes”, “35% No”. The design used in this “virtual poll’
(3.) is a simple random sample.  One, (b) is a stratiﬁed random ample. — Monuc (c) is a confounded ran om sample. is a voluntary (e) is none of the above. Question 2: [3 points total] All densities should be symmetric in order to be valid.
Circle one: [True] 1%) Question 3: [3 points total] In all density curves, the median is less than or equal to the Circle one: [True]
MedMean Med (on [ mean
' MedE 5.. Question 4: [3 points] Suppose we compare two sets of data (data set 1 and data set 2) each
containing 100 values. We discover that, for the two data sets, the sample means are identical and th
sample standard deviations are identical (that is, 351 = $2 and 31 = 32). Thus, the two data sets
also be identical. Circle one: [True] Question 5: [3 points] An accountant reports that 90% of the company’s employees earn less than '
the mean salary for the entire company. Clearly, this must be a mistake since this is imos ‘1. Circle one: [True] Question 6: [3 points} If the correlation between the quantitative variables X and Y is zero, th
X and Y are unrelated. Circle one: [True] Question 7: [12 points total] The following are side by side boxplots for calories found in varieties
of hot dogs. Hot Dog Calories Calories
120 140 160 180 200 100 Beef Pork Chicken I
/
f
z (a) [3 pts] The variet of o t dog having the largest median would be:
A) Beef @ ork C) Chicken / D) Cannot be determined with this image
(b) [3 pts] The variety of hot dog having
A) Beef B Pork e largest range would be: icken D) Cannot be determined with this image (c) [3 pts] The var' ty of hot do « having the largest minimum value would be:
m i k C) Chicken D) Cannot be determined with this image C) Chicken D) Cannot be determined with this image Question 8: [10 points total] In 3. statistics class with 136 students1 the professor records how
much money each student has in their possession during the ﬁrst class of the semester. The histogram
below shows the data collected. :3 >
g o
m :1
:3
3
a
ﬁt N
o 0 20 40 60 80 1 00 1 20 (b) [3 points] The histogram is: _ "
a.) skewed to the left kewed to\th7[ght c.) symmetric d.) none of these choices (0) [4 points] To describe the center . s n a . u a t ' ' tribution, which would be most appro
priate: (circle one) ﬁve number summary "a? and s
‘3' Question 9: [20 points total] A local machine shop manufactures ball bearings for various in
dustries. Since the machines which produce the ball bearings are prone to error, the diameter (in millimeters) of the ﬁnal products vary. Suppose the diameter of a randomly chosen ball bearing
closely follows the N (45, 2.3) distribution. The industry clients have now enacted strict quality guidelines and will reject any ball bearing with a
diameter exceeding 50 millimeters. (a) {10 pts] What proportion of ball bearings would we reject? l LJLDOU\C\ bC) ream (b) [10 pts} What is the diameter found in the top 10% of the largest ball bearings from this distribution?
2% 1.25 X'L—l‘?) 2..“
Z. %
moo ' =2.C\'—\L\: we.
0 1 Z + ‘—\% + q:
Todee: 8qu “mm The {of “mm Question 10: [13 points total] A sample oéerum cholest 01 levels of some men who visited a
cholesterol screening clinic yielded values of: 318 315 315 363 353 359 399 (a) [4 pts] What is the standard deviation in this sample? You may simply write your answer .a>eer\0 06:" 3M8 S
34‘le 99. @ (b)' [4 pts] What is the mode in this sample? / \/ (c) [5 pts] Determine the ﬁve num r summary for this data.
gin “323:3 Q = ’2>\o°o
\ 7 3
Med = eye's O‘K mc‘ Question 11: [8 points total] A report states, “There is a strong positive correlation between X = the number of ﬁreﬁghters at a ﬁre and Y = the amount of damage a ﬁre does. So sending lots of
ﬁreﬁghters just causes more damage”. Explain in 8 sentences or less why it is reasonable for a positive correlation to exist between X and Y
and identify at least one lurking variable in this problem. tom \(ariosae : how bias thifire, ice
H We reoembm. to have, o~ same, Carentim barman
xl bot Pr dim (ECQaﬁOJi mam a ewwﬁmooec
be “the. notober 0 re, ﬁatstare increase2% ClCEBhi mean
“The, don‘t»an mceﬁﬁamk incest].qu \Jr 6 determined on
hOUgJ' \ou2 :, {chmLie. «he We; 5 mega“; rocboirmg more,
{areﬁo‘j ‘é W\U\é W‘eolﬂl 0% may?“ QQWQQE' Question 12: {16 points total] How well does the number of beers a student drinks predict his
or her blood alcohol content? To pursue this question, i have secured a group of willing volunteers
among members of I Pheltu Tht' fraternity. After a careful screening process, I was able to ﬁnd 16
noble fraternity members to sacriﬁce themselves for the advancement of science and participate. Each
member drank a randomly assigned number of 12 oz. cans of beer. Thirty minutes later, a police
ofﬁcer measured their blood alcohol content (BAC, measured in %). A summary is below: Variable Mean Std Dev
beer 2.389 1.984  9%le ’ X
BAC 10.520 5.607  re‘aPOW’V (a) {4 pts] What are the explanatory and respo se variables?
Explﬂha T beer Ream  HQ;
(b) [8' pts] A correSponding scatterplot shows that a linear relationship is reasonable. Find the
equation of the least squares regression line. (Show all work to receive full credit) , , z , — . Leas)
lelrbgq b ,qgga sum 0L 1062.0 Zuﬁz’ﬁﬁ
 \.°\8¥l : V3520  (9,97%
: “:3.st
3; mm : .92588 2.894;. —. Ll_[8'2._
9N —. 5 Laos l b= 2 Laces (c) [4 pts] What percent of the variation observed in the response variable is explained by this
linear regression? Question 13: [3 points total] If Y follows the normal distribution with mean 55 and standard deviation 9, the variable X355 follows which of the following distributions? (a) N(55,0) (b) N(1,9
(55,9) a,“ ‘ 5) ,1) U! ...
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