Exam 1: Stats Start Here

Suppose that a Normal model describes the acidity (pH) of rainwater, and that water tested after last week's storm had a z-score of 1.8. This means that the acidity of that rain …

The distribution below is the number of family members reported by 25 people in the 2010 Census. The best description for the shape of this distribution is

City planners wanted to know how many people live in a typical housing unit so they compiled data from hundreds of forms that had been submitted in various city offices. Summary statistics are shown in the table. 2.53 people s 1.40 people min 1 Q1 1 median 2 Q3 3 max 10 a. Notice that the minimum occupancy and the first quartile are the same. Explain how this can be. b. The city classifies residences housing 4 or more people as "high occupancy". Would you consider 4 occupants to be unusually high? Explain. c. The city bases their garbage disposal fee on the occupancy level of the home or apartment. The annual fee is $40 plus $5 per person, so a single occupant pays $45 and the homes with 10 people pay $40 +$5(10) = $90 a year. What is the median fee paid? And the IQR? d. What are the mean and standard deviation of the garbage disposal fees?

In July 2013, the Federal Drug Administration approved a new version of a drug used to treat opium dependence. The old version of the drug had received complaints about a bitter taste, an aftertaste, and that it took a long time to dissolve. The goal of the new version was to get more patients to take the drug as prescribed by addressing these issues. In addition to these improvements, experimenters monitored the existence and types of side effects of the drug. -Describe the W's, if the information is given: · Who: · What: · When: · Where: · How: · Why:

The boxplots show fuel economy of 2011 model cars for the classes shown. a. Which class offers the car with the best gas mileage, and what is the mileage of that car? b. Which class has the highest median gas mileage, and how much is it? c. Which class of car has the smallest range of fuel economy, and what is it? d. Which class of car has the smallest IQR, and what is it? e. Which class of car generally gets the best mileage? Explain.

The Postmaster of a city's Post Office believes that a Normal model is useful in projecting the number of letters which will be mailed during the day. They use a mean of 20,000 letters and a standard deviation of 250 letters. Draw and clearly label this model.

The SPCA has kept these data records for the past 20 years. If they want to show the trend in the number of dogs they have housed, what kind of plot should they make?

Suppose that a Normal model describes fuel economy (miles per gallon) for automobiles and that a Saturn has a standardized score (z-score) of +2.2. This means that Saturns . . .

Owners of an exercise gym believe that a Normal model is useful in projecting the number of clients who will exercise in their gym each week. They use a mean of 800 clients and a standard deviation of 90 clients. a. Draw and clearly label this model. b. What is the first quartile of the weekly number of clients? [Show work] c. An owner of another gym reports that 5% of the time their gym has fewer than 450 clients, and 40% of the time the gym has more than 1085 clients. What parameters should that owner use for his Normal model? N( $\underline{\quad\quad}$ , $\underline{\quad\quad}$ )

To determine if people's preference in dogs had changed in the recent years, organizers of a local dog show asked people who attended the show to indicate which breed was their favorite. This information was compiled by dog breed and gender of the people who responded. The table summarizes the responses. Female Male Total Yorkshire Terrier 73 59 Dachshund 49 47 Golden Retriever 58 33 Labrador 37 41 Dalmatian 45 28 Other breeds 86 67 Total -Which of the W's are unknown for these data?

Which of the following variables would most likely follow a Normal model?

Book sales A publishing company pays its sales staff $600 a week plus a commission of $0.50 per book sold. For example, a salesman who sold 440 books earned 600 + 0.50(440) =$820. a. The table shows summary statistics for the number of books the large sales staff sold last week. Fill in the table to show the statistics for the pay these people earned. Statistic BooksSold \ Earned Mean 640 Standarddeviation 360 IQR 450 Maximum 1420 b. The newest employee had a pretty good week. Among all the salespeople her pay corresponded to a z-score of +1.80. What was the z-score of the number of books she sold?

Which is true of the data whose distribution is shown? I. The distribution is skewed to the right. II. The mean is probably smaller than the median. III. We should summarize with median and IQR.

The five-number summary of credit hours for 24 students in a statistics class is: Min Q1 Median Q3 Max 13.0 15.0 16.5 18.0 22.0 Which statement is true?

The five-number summary for the weights (in pounds) of fish caught in a bass tournament is: Min Q1 Median Q3 Max 2.3 2.8 3.0 3.3 4.5 a. Would you expect the mean weight of all fish caught to be higher or lower than the median? Explain. b. You caught 3 bass weighing 2.3 pounds, 3.9 pounds, and 4.2 pounds. Were any of your fish outliers? Explain.

The five-number summary for the fuel economy (in miles per gallon) of year 2011 midsize cars is: Min Q1 Median Q3 Max 13 21 23 26 50 a. Would you expect the mean gas mileage of all midsize cars to be higher or lower than the median? Explain. b. One model of Volkswagon gets 34 mpg, one model of Toyota gets 28 mpg, and one model of Bentley gets 13 mpg. Are any of these cars outliers? Explain.

Which of these variables is most likely to follow a Normal model?

The ages of people attending the opening show of a new movie are summarized in the ogive shown. Estimate the IQR of the ages.

Cats and dogs The table shows whether students in an introductory statistics class like dogs and/or cats. $\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\text { Like Dogs }$ start text Like Cats end text Yes No Total Yes 194 21 215 No 110 10 120 Total 304 31 335 a. What is the marginal distribution (in %) of "liking dogs"? b. What is the conditional distribution (in %) of "liking dogs" for students who like cats? c. What kind of display(s) would you use to examine the association between "liking dogs"and "liking cats"? (Just name a graph.) d. Do "liking dogs" and "liking cats" appear to be independent? Give statistical evidence to support your conclusion.

Which of the following summaries are changed by adding a constant to each data value? I. the mean II. the median III. the standard deviation