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North Seattle Community College Winter 2011 ELEMENTARY STATISTICS 2617 MATH 109 - Section 05, Practice Questions for Test 1 – Chapter 1 and 2 1) Identify population and sample in the following study: a) In a recent survey, 250 college students at Union College were asked if they smoked cigarettes regularly. b) A study of 146 credit cards found that the average late fee is $27.46. 2) Determine whether the numerical value describes a parameter or a statistics: a) A recent survey of a sample of 450 college students reported that the average weekly income for students is $325. b) The average weekly income for all students is $405. 3) The grade point averages of five students are listed in the table. Which data are qualitative data and which are quantitative data? Student GPA Sally 3.22 Bob 3.98 Cindy 2.75 Mark 2.24 Kathy 3.84 4) Determine level of measurement for each of the following? a) Morning commute (in miles) of teachers at Midtown High School b) Ocean temperature at seven beaches along the east coast of the U. S. c) 1st, 2nd, and 3rd place finishers of the 2000 Boston Marathon d) Account numbers of the clients of the S & H Bank 5) Which method of data collection would you use for each of the following studies? a) a study of the effect of Glucotrol on a diabetics sugar control. b) a study of the effect of electrical shock to the human body. c) a study to determine the average number of children per couple in the U. S. 6) You are conducting a survey at the college you attend to determine the number of students who own a personal computer. The college consists of four campuses, one each on the north, south, east, and west sides of the city. Since you attend the south campus, you decide to ask 200 of the 5,000 students from that campus. Which sampling technique did you use? 7) The number of years of service of 60 randomly chosen Jacksonville firefighters is as follows. a) Find the missing values indicated in the table i), ii) and iii). b) Calculate the mean and standard deviation of the years of service for the 60 firefighters. 8) Which set of data is represented by the histogram below? (choose one) a) 1, 3, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6 b) 3, 5, 5, 8, 9, 11, 12, 13, 13, 14, 14, 15, 15, 17, 17, 17, 18, 18, 20 c) 1, 5, 6, 7, 9, 9, 10, 13, 13, 14, 14, 15, 15, 17, 18, 19, 20, 20 d) 4, 6, 7, 8, 9, 10, 10, 13, 13, 13, 14, 16, 17, 17, 18, 19, 20, 21 9) Suppose you are taking a class in which your final grade is figured as follows: 50% from your test mean, 25% from your final exam score, 15% from your quiz mean, and 10% from your homework grade. If your grades are 80 (test mean), 88 (final exam), 75 (quiz mean), and 98 (homework), what is the weighted mean of your scores? 10) Construct an ordered stem-and-leaf diagram describing the following data: 106, 103, 107, 111, 113, 116, 113, 119, 119, 120, 125, 134, 136, 134. 11) Find the measures of central tendencies (mean, median, mode) a) For the following lengths of operating times in months of 15 randomly selected car batteries: 18, 21, 22, 22, 23, 23, 23, 25, 25, 26, 27, 30, 30, 31, 32. b) Suppose the last car battery sampled above lasted 60 months instead of 32 months. Find the mean, median, mode of this new set of data. c) How has the change in the data from a) to b) impact the mean, median and mode. 12) Find the measures of variation (range, standard deviation, and variance) for the following sample data: 5, 8, 9, 10, 15, 21, 27, 32 13) Suppose a data set has a mean of 8 and a standard deviation of 2. What proportion of the data values are between a) 2 and 14 b) 8 and 12 c) 6 and 8 14) A set of bell-shaped distributed data has mean 500 and standard deviation 40. Between what two values does approximately 95% of the data lie? 15) The mean price of houses in a certain neighborhood is $100,000, and the standard deviation is $10,000. Find the price range for which at least 75% of the houses will sell. 16) Identify the following histograms as symmetric, uniform, skewed-left, skewed-right: (a) (b) (c) 17) For questions #1 through #11, please refer to the sample data below. The following are GPA’s of randomly selected students. The values are sorted from low to high. { 1.54, 1.59, 1.67, 1.86, 1.94, 2.06, 2.08, 2.43, 2.53, 2.63, 2.91, 2.93, 3.05, 3.12, 3.32, 3.54, 3.80, 3.81, 4.00 }. a) Compute the sample mean. b) Compute the standard deviation and variance. c) Compute the median. d) Compute the mode. e) Compute the range. f) Compute the lower (Q1) and upper quartiles (Q3) and the inter-quartile range. g) Construct a frequency table and histogram, with the first lower class limit equal to 1.54. Use 5 classes. 18) A student receives the following grades, with an A worth 4 points, a B worth 3 points, a c worth 2 points and a D worth 1 point. What is the student’s mean grade point score? A in 1 four-credit class B in 2 three-credit classes C in 1 three-credit class D in 1 two-credit class 19) A salesperson at a company sold $6,903,435 of hardware equipment last year, a figure that represented the eighth decile of sales performance at the company. What can you conclude about the salesperson’ performance? 20) Assuming equal ranges and sample sizes, will a set of bell-shaped distributed data or a set of uniformly distributed data have the greater standard deviation. Explain your reasoning.