Review Questions Part 2 (MP 4 and 5) College Statistics. 1. Identify each of the following variables as qualitative or quantitative:

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1 Review Questions Part 2 (MP 4 and 5) College Statistics Name: 1. Identify each of the following variables as qualitative or quantitative: (a) number of pets in family (b) County of residence (c) Choice of auto to buy (domestic or import) (d) Distance (in miles) of commute to school 2. Identify each of the following variables as continuous or discrete: (a) the weight of a dog (b) the number of people you have dated in the past month (c) the total playing time of a CD (d) the number of courses for which a student has received credit (e) the amount of money in your pocket 3. ebay is a popular Internet company for personal auctioning. Let s consider some data from sales of a PDA during May The final prices (in dollars) at which the items were sold were 235, 225, 225, 240, 250, 250, 210, 250, 249, 255, 200, 199, 240, 228, 255, 232, 246, 210, 178, 246, 240, 245, 225, 246, 225 (a) Construct a stem-and-leaf plot. (b) Summarize what this plot tells you about the data

2 4. The mean and median both describe the center of data. (a) Why is the median sometimes preferred? Give an example. (b) Why is the mean sometimes preferred? Give an example. 5. According to sportingnews.com, in 2003 professional baseball players earned a mean salary of $2.5 million and a median salary of $800,000. What do you think causes these two values to be so different? 6. For sample heights of high school seniors, the males has a mean of 71 and s = 3 and the females had a mean of 65 and s = 3. (a) Use the Empirical Rule to describe the distribution of heights for males. (b) The standard deviation for the overall distribution (combining females and males) was 4. Why would you expect it to be larger than the standard deviations for the separate male and female height distributions?

3 7. The following data represent survey results about how many miles per day employees of a company use public transportation. The sample values were Identify the five number summary and sketch a box plot. Why does the box plot not have a left whisker? 8. A World Health Organization study of health in various countries reported that in Canada, systolic blood pressure readings have a mean of 121 and a standard deviation of 16. A reading above 140 is considered to be high blood pressure. (a) What is the z-score for a blood pressure reading of 140? How is this z- score interpreted? (b) The systolic blood pressure values have a bell-shaped distribution. Report intervals within which about 95% of the systolic blood pressure values fall. 9. What is the preferred American pet? According to Statistical Abstract of the United States and the American Veterinary Medical Association, of pet-owning households, 36% have a dog and 32% have a cat. In 2002, vet care was sought be 85% of households owning a dog and by 67% of households owning a cat. (a) What is the population being considered? (b) Do you think these statistics were based in (i) observational study? (ii) experiment? (iii) sample survey? (iv) census?

4 10. The 2000 U.S. census reported the frequencies in the following table for how workers 16 years and over commute to work. Method used Frequency car, truck, or van-drove 97,102,050 alone car, truck, or vancarpooled 15,634,051 Public transit 6,067,703 walked 3,758,982 other 1,532,219 worked at home 4,184,223 total 128,279,228 (a) What is the probability that a randomly selected worker commuted to work in a car, truck or van? (b) Given that a person commuted to work in a car, truck, or van, what is the probability of car pooling? 11. State whether each number listed below can be the probability of some event? (a).71 (b) 4.1 (c) 1/8 (d) 150 % 12. Two cards are drawn at random from a standard deck. (A standard deck has 52 cards: 13 hearts, 13 diamonds, 13 clubs, and 13 spades) (a) If the first card is replaced before the second is drawn, what is the probability that both cards will be hearts? (b) If the first card is not replaced before the second is drawn, what is the probability that both cards will be hearts?

5 13. According to the Textbook of Medical Physiology, 9% of the population has blood type B. Suppose we choose 18 people at random from the population and test the blood type of each. What is the probability that three of these people have blood type B? 14. A fair quarter is flipped three times. (a) Find the probability of getting exactly 3 tails. (b) Find the probability of getting two or more heads. 15. USA Today reported that about 20% of all people in the United States are illiterate. Suppose that you take seven people at random off a city street. (a) Find the mean and standard deviation of this probability distribution. (b) Would it be unusual to find that five of those seven people are illiterate?

6 16. A vending machine automatically pours soft drinks into cups. The amount of soft drink dispensed into a cup is normally distributed with a mean of 7.6 oz and a standard deviation of 0.4 oz. (a) Estimate the probability that the machine will overflow an 8-oz cup. (b) Estimate the probability that the machine will not overflow an 8-oz cup. (c) The machine has just been loaded with 850 cups. How many of these do you expect will overflow when served? 17. For a given population of high school seniors, the American College Testing (ACT) exam, in mathematics has a mean of 18 and a standard deviation of 6. (a) What is the probability that a randomly selected high school senior s score on the math part of the ACT will be between 12 and 28? (b) What score represents the 90 th percentile?