1. A teacher wishes to know whether the males in his/her class have more

conservative attitudes than the females. A questionnaire is distributed assessing

attitudes and the males and the females are compared. Is this an example of

descriptive or inferential statistics?

2. A cognitive psychologist is interested in comparing two ways of presenting

stimuli on sub- sequent memory. Twelve subjects are presented with each method

and a memory test is given. What would be the roles of descriptive and

inferential statistics in the analysis of these data?

3. If you are told only that you scored in the 80th percentile, do you know from

that description exactly how it was calculated? Explain.

4. A study is conducted to determine whether people learn better with spaced or

massed practice. Subjects volunteer from an introductory psychology class. At

the beginning of the semester 12 subjects volunteer and are assigned to the

massed-practice condition. At the end of the semester 12 subjects volunteer and

are assigned to the spaced-practice condition. This experiment involves two

kinds of non-random sampling: (1) Subjects are not randomly sampled from

some specified population and (2) subjects are not randomly assigned to

conditions. Which of the problems relates to the generality of the results? Which

of the problems relates to the validity of the results? Which problem is more

serious?

5. Give an example of an independent and a dependent variable.

6. Categorize the following variables as being qualitative or quantitative:

Rating of the quality of a movie on a 7-point scale

Age

Country you were born in

Favorite Color

Time to respond to a question

8. You know the minimum, the maximum, and the 25th, 50th, and 75th percentiles

of a distribution. Which of the following measures of central tendency or

variability can you determine?

mean, median, mode, trimean, geometric mean, range, interquartile range,

variance, standard deviation

9. For the numbers 1, 3, 4, 6, and 12:

Find the value (v) for which ?(X-v)2 is minimized.

Find the value (v) for which ?|x-v| is minimized.

10. Your younger brother comes home one day after taking a science test. He says

that some- one at school told him that "60% of the students in the class scored

above the median test grade." What is wrong with this statement? What if he had

said "60% of the students scored below the mean?

?

Problem No. 4.6 / 10 pis, All the sixth-graders in a certain middle school took a standardized test. A total of 87% of the students were found to be proficient in reading. 77% were found to be proficient in mathematics. 67% were found to be proficient in both reading and mathematics. A student is chosen at random. 1) What is the probability that the student is proficient in mathematics but not in reading? 2) What is the probability that the student is proficient in reading but not in mathematics? 3) What is the probability that the student is proficient in neither reading nor mathematics? Show your explanations. Displaying only the final answer is not enough to get credit. Note: round numerical answers to the second decimal place where applicable.6. Out of 650 applicants who intend to major in the Mathematical Sciences, 507 scored 700 or higher on the GRE-Quantitative test. Out of 400 applicants who intend to major in Physics or Astronomy, 108 scored below 700 on the GRE-Quantitative test. Which group of applicants has the higher probability of scoring below 700 on the GRE-Quantitative test? Physics or Astronomy Mathematical Sciences Both groups have the same probability. We can't tell which group has the higher probability.5. (4 points each) The chair of the Department of Mathematics and Statistics needs to appoint a faculty committee consisting of 5 mathematics and 6 statistics faculty. There are 20 mathematics and 15 statistics faculty members in the department. (a) In how many ways can he select such a committee? (Note: set up a numerical expression using fractions, factorials, and binomial coefficients as necessary; you don't have to evaluate it./ (b) What is the probability that randomly selected 11 people will actually form such a committee? Note: Set up a numerical expression using fractions, factorials, and binomial coefficients as necessary; you don't have to evaluate it./Q11. In a high school graduating class of 100 students, 54 studied mathematics, 69 studied history, and 35 studied both mathematics and history. If one of these students is selected at random, find the probability that (a) The student took mathematics or history; (b) The student did not take either of these subjects; (c) The student took history but not mathematics. Q12. Interest centers around the life of an electronic component. Suppose it is known that the probability that the component survives for more than 6000 hours is 0.42. Suppose also that the probability that the component survives no longer than 4000 hours is 0.04. (a) What is the probability that the life of the component is less than or equal to 6000 hours? (b) What is the probability that the life is greater than 4000 hours