STAT303: Secs 509-511Spring 1999Exam #1Fo r m AInstructor: Julie Hagen Carroll1. Don’t even open this until you are told to do so.2. Be sure to mark your section number (509, 510 or 511) and your test form (A, B, C or D) on thescantron!3. Sign your name where indicated on your scantron and write your Thursday section number and computernumber beside it. Also, you must place your scantron in the correct section stack (for next Thursday).4. There are 20 multiple-choice questions on this exam, each worth 5 points. There is partial credit. Pleasemark your answers clearly on the scantron. Multiple marks will be counted wrong.5. You will have 60 minutes to finish this exam.6. If you are caught cheating or helping someone to cheat on this exam, you both will receive a grade ofzero on the exam. You must work alone.7. This exam is worth 100 points, and will constitute 25% of your final grade.8. Good luck!1STAT303: 509-511 Exam #1, Form A Spring 19991. What is the approximate correlation between xand y above?A. since the slope is less than 1, it can’t bestrongB. strongly positiveC. moderately positiveD. 0.737401E. can’t tell from graph2. If we added the point (5,25) to the graph above,what would change?A. (5, 25) is approximately the mean of thedata, so nothing would change muchB. (5, 25) would be an influential point, so theslope, intercept and correlation would allchangeC. (5, 25) would be an outlier, so the correla-tion would change, but the slope and inter-cept would not change muchD. (5, 25) would be an outlier, so the slope,intercept and correlation would all changeE. (5, 25) would be an influential point, so thecorrelation would change, but the slope andintercept would not change much3. The point (28, 10) (if added to the graph above)would be consideredA. a ’good’ point since it will fall on the lineB. an outlierC. an influential pointD. a ’bad’ point since the correlation would goupE. a ’bad’ point since the slope would go down4. Let X ∼ N (2, 22). What is P (2 <X<5)?A. 0.9987B. 0.9332C. 0.0013D. 0.4332E. 0.53325. Which of the following is a categorical variable?A. Social Security NumberB. Classification: senior, junior, etc.C. days of the weekD. All of the above are categorical variables.E. Exactly two of A, B, and C are categoricalvariables.6. Which of the following is/are true?A. A uniform distribution can never have anoutlier.B. A normal distribution can have outliers oneither end, but not both.C. A constant distribution has a standard de-viation of zero.D. All of the above are true.E. Only 2 of A, B and C are true.7. If Z ∼ N(0, 12), what is P (−1.56 >Z>−2.05)?A. -0.0392B. 0.0392C. -0.0594D. 0.0594E. 0.02028. If X ∼ N(4, 32), what is x∗if P (X>x∗)=0.20?A. 1.48B. -0.84C. 0.84D. 7E. 6.529. Which of the following statements is/are true?A. If the least squares line has a slope, b1=0, then the (x, y) points must be randomlyscattered.B. If the least squares line has a slope, b1=1,then the correlation between x and y mustbe +1 or −1.C. If the correlation coefficient between x andy, r = 0, then there is no relationship be-tween x and y.D. All of the above statements are true.E. None of the above statements is true.2STAT303: 509-511 Exam #1, Form A Spring 199910. What does the normal quantile plot above tellus about the shape of the data distribution?A. Since it’s a normal quantile plot, the datais normal.B. We can’t say the data is normal, but wecan’t tell what its shape is.C. The data is skewed left(negatively).D. The data is skewed right(positively).E. The data is uniform.11. Again, let X ∼ N(2, 82). If Y =2− 5X,whatare µYand σY?A. µY= −8, σY= −38B. µY=8,σY=38C. µY= −8, σY= −40D. µY= −8, σY=40E. µY=8,σY=40--------------------------------X |-2|0|2|5--------------------------------p(X) | 0.4 | 0.3 | 0.2 | 0.1--------------------------------12. What are the mean, µX, and standard deviation,σX, of the population represented above?A. µX=0.1, σX=2.21B. µX=1.7,σX=1.42C. µX= −0.1, σX=4.9D. µX=1.7,σX=4.9E. µX=0.1,σX=4.913. Which of the following indicate that the data isnormally distributed?A. The mean is approximately equal to the me-dian.B. The normal quantile plot shows the datapoints following the line on the plot.C. The boxplot is symmetric.D. All of the above indicate that the data isnormally distributed.E. Exactly two of the above indicate that thedata is normally distributed (excluding D.).MasterCard-----------------------------Visa | Yes | No | Total-----------------------------Yes | 4200 | 2800 | 7000-----------------------------No | 1800 | 1200 | 3000-----------------------------Total | 6000 | 4000 | 10000-----------------------------14. The table above shows the number of students(out of a total of 10,000) with a MasterCard, aVisa card or both. Which of the following aretrue?A. Having a MasterCard and a Visa card aremutually exclusive events since you don’tneed but one. (Since you can use either cardat most places, there’s no point in havingboth).B. Having a MasterCard and a Visa card areindependent events since you are just aslikely to have a Visa card whether you havea Mastercard or not.C. Having a MasterCard and a Visa card arenot independent events since you are morelikely to have a MasterCard if you have aVisa card than you are if you don’t have aVisa card.D. Having a MasterCard and a Visa card aremutually exclusive events since it doesn’tmatter which one you have.E. Having a MasterCard and a Visa card areindependent events since the greatest prob-ability is to have both cards.15. Find z∗such that P (−z∗<Z<z∗)=0.30?A. z∗=0.3850B. z∗=0.15C. z∗=0.5596D. z∗=0.6179E. z∗=1.033STAT303: 509-511 Exam #1, Form A Spring 199916. Which of the following statements describe theboxplots above correctly?A. all three are normalB. 1 and 2 are normal, but 3 is uniformC. only2isnormal,1and3areuniformD. 1 is normal, 2 is unknown, and 3 is uniformE. all three are uniform17. If the mean, µ = 5 and the standard deviation,σ =2,thenA. at least 95% of the observations fall between1and9.B. at least 75% of the observations fall between1and9.C. approximately 95% of the observations fallbetween 1 and 9.D. All of the above are true statements.E. Exactly two of A, B and C are true state-ments.18. Which of the following is/are true?A. If A and B are mutually exclusive, then P (Aor B)=P (A)+P (B).B. If A and B are mutually exclusive, thentheir probabilities must sum to 1.C. If A and B are independent,
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