2009
Sample DSCI-207-01/02
Spring Mid-Term Questions
These questions were used in Fall 2008. They will give you an idea of the type of questions to expect.
Instructions: For multiple choice questions, circle the letter of the BEST answer. For short answer questions, confine your answers to the space reserved. Unless otherwise noted, each question in this exam counts ___ points. This exam counts ___% of your semester grade. MULTIPLE CHOICE 2 Circle the letter of the BEST answer.
In the business world, statistics are often used to a describe our customers, suppliers, employees, and products b draw conclusions and make decisions c persuade or sell others d all of the above e none of the above Descriptive statistics are primarily used to a collect and classify data b summarize and organize data c analyze and interpret data d all of the above e none of the above Using statistics to intentionally distort facts or lead others to an inaccurate conclusion is a a good way to maximize profit b considered a normal business practice c unethical or unprofessional d good, unless you get caught As a tool of Decision Sciences, the primary purpose of statistics is to help us a make better decisions b employ fewer people c buy fewer computers and other equipment d reduce paperwork A students hair color can be black, brown, red, blonde, or other. This is an example of a quantitative data b qualitative data c continuous data d discrete data e none of the above Which of the following would usually be an experimental unit? a a class of students or a group of employees b an individual student or employee c all the students enrolled at SLU or employed by Big Company d a random sample of 50 students or employees
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14 Measures of central tendency are designed to tell us the a location of a set of data along a number scale b degree of variation in the data c overall shape of the data d bias of the data or the observer
15 Range is a a simple measure of central tendency b complex measure of central tendency c simple measure of variation d complex measure of variation
1) Probabilities of different types of vehicle-to-vehicle accidents are shown below: Accident Car to Car Car to Truck Truck to Truck Probability 0.70 0.11 0.19
Find the probability that an accident involves a car. A) 0.81 B) 0.19 C) 0.70 D) 0.11 2) Four hundred accidents that occurred on a Saturday night were analyzed. The number of vehicles involved and whether alcohol played a role in the accident were recorded. The results are shown below: Number of Vehicles Involved 1 2 3 or more 52 97 21 28 175 27 80 272 48
Did Alcohol Play a Role? YES NO TOTAL
TOTAL 170 230 400
What is the probability that an accident involved a single car without the effect of alcohol? A) B) C) D) 13/100 1/5 7/100 7/20
3) A number between 1 and 10, inclusive, is randomly chosen. Events A and B are defined as follows. A: {The number is even} B: {The number is less than 7} Identify the sample points in the event A ? B. A) B) C) D) {1, {1, {2, {1, 2, 2, 4, 2, 3, 4, 5, 6, 7, 9} 3, 4, 5, 6, 8, 10} 6} 3, 4, 5, 6, 7, 8, 10}
10) The overnight shipping business has skyrocketed in the last ten years. The single greatest predictor of a company's success is customer service. A study was conducted to determine the customer satisfaction levels for one overnight shipping In business. addition to the customer's satisfaction level, the customers were asked how often they used overnight shipping. The results are shown in the following table: Satisfaction Level High Medium Low 250 140 10 140 55 5 70 25 5 460 220 20
Frequency of Use <2 per month 2-5 per month >5 per month TOTAL
TOTAL 400 200 100 700
Suppose that one customer who participated in the study is chosen at random. What is the probability that the customer had a high level of satisfaction and used the company two to five times per month? A) B) C) D) 1/5 9/35 26/35 33/35
17) Suppose a basketball player is an excellent free throw shooter and makes 92% of his free throws (i.e., he has a 92% chance of making a single free throw). Assume that free throw shots are independent of one another. Find the probability that the player will make five consecutive free throws. A) B) C) D) 0.3409 0 0.6591 1
22) Consider the given discrete probability distribution. Find the probability that x exceeds 5. X P(X) A) B) C) D) 0.71 0.97 0.29 0.68 3 .03 5 ? 6 .02 9 .27
28) Use the standard normal distribution to find P(-2.25 < z < 1.25). A) B) C) D) .0122 .8821 .8944 .4878
31) A physical fitness association is including the mile run in its secondary-school fitness test. The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 460 seconds and a standard deviation of 60 seconds. Find the probability that a randomly selected boy in secondary school can run the mile in less than 322 seconds. A) B) C) D) .0107 .9893 .4893 .5107
PROBLEMS
Show all your work and circle or mark your answer [ 52 52 55 58 60 ]
18 [10 points] Using the following five data points a b c Calculate the mean value This data set is (circle ONE): Calculate the standard deviation
Skewed Left
Symmetrical
Skewed Right
19 [10 points] Assume the following data set represents ages of a group of Saint Louis residents 12 28 30 32 34 35 39 42 45 50 52 52 55 58 60 61 63 65 68 92 a b c d e f g h i j How many experimental units are there? _______________________________________________________ _______________________________________
When calculating this groups mean, what is the value of n? What is the median age? What is the groups mode? What is the groups range?
_______________________________________________________ _______________________________________________________ _______________________________________________________
Amy ranks third in this group. What is her age? ____________________________________________________ Johns age is at the 80th percentile. How old is he? What are the outlier value(s)? _________________________________________________
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How many people are in the third quartile? _______________________________________________________ How many people are in the seventh decile? _______________________________________________________
20 ASSUME the mean age for a population is 50 and the standard deviation is 10. Alex claims that most of the people are aged 40 to 60. Is that claim true? Prove or disprove the claim.
17 Asampleof50observationshasbeenmade.Oneobservedvalueissosmallthat thereislessthana3%chance(p=0.0294)thatanyobservationwillbesmaller. Howmanystandarddeviationsbelowthemeanistheobservationinquestion?