11. According to the National Association of College Stores (NCAS), students spend, on average, $655 on books per year. Suppose the standard deviation for the amount of money students spend on books per year is $240.

1. (a) What is the probability that a randomly selected student will spend more than $750 on a book in a year?
2. (b) What is the probability that in a random sample of 35 students, the average amount of money of money they spend on books will be more than $750 on a book in a year?
3. Multiple Choice: Suppose a researcher would like to perform a test to determine the proportion of individuals with lung cancer that are smokers. A researcher goes to a local hospital and asks 20 lung cancer patients whether or not they are smokers. What type of test statistic would you calculate for this test? (a) Z (b) t (c) 2
4. Multiple Choice: I would like to know if there is a relationship between whether or not a daughter has ever had breast cancer and whether or not her mother ever had breast cancer. What type of test statistic would you calculate for this test? (a) Z (b) t (c) 2
5. Multiple Choice: Trends in marriage have changed over time. Suppose a researcher would like to know the average age at which a woman gets married. He takes a sample of 100 married women. What type of test statistic would you calculate for this test? (a) Z (b) t (c) 2

15. Suppose that in a certain large class, 60% of the students are males.

1. (a) Make a box model to represent this.
2. (b) What is the average of this box?
3. (c) What is the standard deviation of this box?
4. (d) Suppose the professor picks 50 students at random. How many males would you expect the pro- fessor to select?
5. (e) For these 50 randomly selected students, what is the standard error for the number of males the professor selects?

16. Below is a table of class standing for students in my class during a previous semester. Calculate the relative frequencies and add them to the table above.

Class Standing	Frequency	Relative Frequency
Freshman	9
Sophomore	57
Junior	53
Senior	41
Total	160

17. A sample of students were asked to rank their looks compared to the looks of others on a scale from 1 to 10. A 10 means they feel they are more attractive than everyone else while a 1 means they feel they are less attractive than everyone else. The data is below:

The data are summarized below.

(a) Estimate the average rank all students would give themselves based on their looks.

(b) Interpret your results from part a.