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Material Type: Exam; Professor: Wei; Class: Prob & Stat I; Subject: Mathematics; University: University of North Carolina at Pembroke; Term: Spring 2006;
Typology: Exams
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MAT 328 -- 01 Probability and Statistics I Spring 2006 Exam 1 Date: 02/24/ Name:_____________________________________ Code | | | | Write your full name and class code clearly in the spaces above. Work independently. Show all necessary steps and details of your work. 75 minutes. Total score is 100. Good luck! Answer each question on a separate paper. Please do not write your solutions on the test. Data A: “Record High Temperatures” for the 50 states of the United States (sorted order): 100 104 105 105 105 106 107 108 109 109 110 110 110 110 110 111 111 112 112 112 112 113 113 114 114 114 114 114 115 116 116 117 117 117 118 118 118 118 118 118 119 120 120 120 120 121 122 122 127 134
1. (35 pts, 5 pts each) Frequency analysis / exploratory data analysis: Limits Boundaries Midpoint Frequency Cumulative Frequency 99.5-104.5 102 2 104.5-109.5 107 8 109.5-114.5 112 18 114.5-119.5 117 13 119.5-124.5 122 7 124.5-129.5 127 1 129.5-134.5 132 1 (1) The above frequency distribution for Data A is obtained by using 7 classes (equal width). Complete the remaining columns: Limits and Cumulative Frequency; (2) Draw the frequency histogram (use boundary points); (3) Draw the frequency polygon (use Midpoints); (4) Draw the Ogive (i.e., cumulative frequency graph; use boundary points); (5) Compute the Five-number summary (min, max, quartiles) and draw the Box-and-whisker diagram; (6) Explain the distribution of data (temperatures) based on (2), (3) and (5). (7) If the Stem-and-Leaf Display is used for this data, a reasonable choice of stems should be the first two digits of these data values (so the stems are 10, 11, 12, and 13). Explain why. 2. (4+4+2 = 10 pts) Find the (sample) mean, variance and standard deviation for the grouped data obtained in part (1) of above question 1 (Give the formula and data only. Do not compute the final results). Data A is considered as a sample. 3. None 4. (20 pts, 5 pts each) In how many different ways can 4 married couples attending a concert be seated in a row of eight seats (1) if there are no restrictions? (2) if each married couple is seated together? (3) if the members of each sex are seated together? (4) Assume the eight people are seated randomly. Compute the probability P(“each married couple is seated together or the members of each sex are seated together”).
5. (20 pts, 5 pts each) You are going to toss a coin repeatedly in successive trials until you observe a head for the first time, and then you are going to stop. (1) Draw a tree diagram that is used to determine the outcomes; (2) List at least 4 possible outcomes; (3) Express the event “at least 3 tosses are required” in terms of the outcomes; (4) Compute the probabilities P(“at least 3 tosses are required before the experiment terminates”) and P(“the process never stops”), respectively. 6. (15 pts) Let W equal the number of feet between consecutive bad records on a computer tap. Ten observations of W are 67 16 7 35 97 28 74 5 9 37 Could the p.d.f. f(w) = (1/40) e– w/40, 0 w < be a satisfactory model? Hint: Draw the q-q plot of quantile of order k/(10+1) to answer the question. w F(w) = P(W w) = f(t) dt = 1 – e- w/40^ for w 0. - Set k/11 = F(qk) = 1 – e-qk/40^ for k = 1, 2, …, 10. Then qk = - 40 ln(1 – k/11) = 40 ln[11/(11-k)].