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Maryland STAT 230 Midterm Exam




Question;STAT 230 100 POINTSMidterm Exam (120 POINTS POSSIBLE)Circle the best answer for each questionUse the following data for questions 1 through 4: 5,12,6,8,5,6,7,5,12,4.1. The median isa. 5b. 6c. 7d. 8e. None of the above2. The mode isa. 5b. 6c. 7d. 8e. None of the above3. The mean isa. 5b. 6c. 7d. 8e. None of the above4. The 75th percentile isa. 5b. 6c. 7d. 8e. None of the above Use the following data for questions 5 through 9: 3,5,12,3,2.5. The variance isa. 80b. 4.062c. 13.2d. 16.5e. None of the above6. The standard deviation is a. 8.994b. 4.062c. 13.2d. 16.5e. None of the above7. The coefficient of variation isa. 72.66%b. 81.24%c. 264%d. 330%e. None of the above8. The range isa. 1b. 2c. 10d. 12e. None of the above9. The interquartile range isa. 1b. 2c. 10d. 12e. None of the above10. If A and B are independent events with P(A) = 0.4 and P(B) = 0.6, then P(A l B) =a. 0.76b. 1.00c. 0.24d. 0.2e. None of the above = 0.411. If A and B are independent events with P(A) = 0.2 and P(B) = 0.6, then P(A U B) =a. 0.62b. 0.12c. 0.60d. 0.68e. None of the above12. If A and B are independent events with P(A) = 0.05 and P(B) = 0.65, then P(A l B) =a. 0.05b. 0.0325c. 0.65d. 0.8e. None of the above13. If A and B are mutually exclusive events with P(A) = 0.3 and P(B) = 0.5, then P(A U B) =a. 0.30b. 0.15c. 0.00d. 0.8e. None of the above14. If A and B are independent with P(A) = 0.3 and P(B) =0.5, then P(A intersect B) =a. 0.00b. 0.15c. 0.8d. 0.2e. None of the above15. A lottery is conducted using three urns. Each urn contains chips numbered from 0 to 9. One chip is selected at random from eachurn. The total number of sample points in the sample space isa. 30b. 100c. 729d. 1000e. None of the above16. A six-sided die is tossed three times. The probability of observingthree ones in a row isa. 1/3b. 1/6c. 1/27d. 1/216e. None of the above17. A perfectly balanced coin is tossed 6 times and tails appears on all six tosses. Then, on the seventh tossa. tails cannot appearb. heads has a much larger chance of appearing than tailsc. tails has a better chance of appearing than headsd. heads must appeare. None of the above 18. In a questionnaire, respondents are asked to mark their gender as male or female. Gender is an example of the a. ordinal scale b. nominal scale c. ratio scale d. interval scale19. A random variable that can assume only a finite number of values is referred to as a(n)a. infinite sequenceb. finite sequencec. discrete random variabled. discrete probability functione. None of the above20. A continuous random variable may assume a. any value in the interval or collection of intervals b. only integral values in an interval or collection of intervals c. only fractional values in an interval or collection of intervals d. only the positive integral values in an interval e. None of the above21. What is the probability that among the students in the sample exactly two are female if 8 students are randomly selected from a large student body that is 60% female?a. 0.0896b. 0.2936c. 0.0413d. 0.0007e. None of the above22. The number of electrical outages in a city varies from day to day. Assume the following probability for x (number of outages) x f(x)0 0.801 0.152 0.043 0.01 The mean and standard deviation for the number of outages area. 2.6 and 5.77b. 0.26 and 0.577c. 3 and 0.01d. 0 and 0.8e. 1.25 and 1.2523. The weight of an object is an example ofa. a continuous random variableb. a discrete random variablec. either a continuous or a discrete random variable, depending on the weight of the objectd. either a continuous or a discrete random variable, depending on the units of measuree. None of the above24. Four percent of the customers of a mortgage company default on their payments. A sample of five customers is selected. What is the probability that exactly two customers in the sample will default on their payments?a. 0.2592b. 0.0142c. 0.9588d. 0.7408e. 0.000025. A local bottling company has determined the number of machine breakdowns per month and their respective probabilities as shownbelow: Number of Breakdowns Probability0 0.151 0.352 0.253 0.204 0.05 The expected number of breakdowns per month isa. 2b. 1.65c. one since it has the highest probabilityd. at least 4e. None of the above26. The Poisson probability distribution is a a. continuous probability distributionb. discrete probability distributionc. uniform probability distributiond. normal probability distributione. None of the aboveUsing the following probability distribution for questions 27 and 28 x f(x)10.220.330.440.127. The expected value of x equals a. 24 b. 25 c. 30 d. 100 e. None of the above 28. The variance of x equalsa. 9.165b. 84c. 85d. 93.33e. None of the aboveFor questions 29 through 33 consider the following: The random variable x, which is the number of occurrences of an event over an interval of ten minutes. It can be assumed that the probability of an occurrence is the same in any two time periods of an equal length. It is known that the mean number of occurrences in ten minutes is 5.3.29. The random variable isa. Bernoullib. Poissonc. Binomiald. Unknowne. None of the above30. The random variable x is a. discreteb. continuousc. either a or b depending on how the interval is definedd. not enough information is givene. None of the above31. The expected value of the random variable x is a. 2b. 5.3c. 10d. 2.30e. None of the above32. The probability that there are 8 occurrences in ten minutes isa..0241b..0771c..1126d..9107e. None of the above33. The probability that there are less than 3 occurrences isa..0659b..0948c..1016d..1239e. None of the above34. Z is a standard normal random variable. The P(-1.20< =Z<=1.50) =a. 0.0483b. 0.3849c. 0.4332d. 0.8181e. None of the above35. The probability of a player weighing more than 241.25 pounds on a team with the mean weight of 200 pounds and a standard deviation of 25pounds isa. 0.4505b. 0.0495c. 0.9505d. 0.9010e. None of the above 36. Five hundred residents of a city are polled to obtain information on voting intentions in an upcoming city election. The five hundred residents in this study is an example of a(n)a. Censusb. Samplec. observationd. population 37. The process of analyzing sample data in order to draw conclusions about the characteristics of a population is calleda. descriptive statisticsb. statistical inferencec. data analysisd. data summarization 38. The sum of the percent frequencies for all classes will always equala. Oneb. the number of classesc. the number of items in the studyd. 100Exhibit 2-2A survey of 800 college seniors resulted in the following crosstabulation regarding their undergraduate major and whether or not they plan to go to graduate school.Undergraduate MajorGraduate School Business Engineering Others TotalYes 70 84 126 280No 182 208 130 520Total 252 292 256 800 39. Refer to Exhibit 2-2 above. Of those students who are majoring in business, what percentage plans to go to graduate school?a. 27.78b. 8.75c. 70d. 72.22The manager of Corner Convenience Store would like to know how quickly customers are able to make their purchases. The manager observed customers and recorded the amount of time (in seconds) it took for each customer to check out. She then constructed the following chart: 40. Refer to Exhibit 3-3 above.What type of chart is this? a. Paretob. Ogivec. Histogramd. BarChart


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