Laptop use in middle school. Refer to the American

Laptop use in middle school. Refer to the American Secondary Education (Fall 2009) study of 106 middle school students’ usage of laptop computers, Exercise 7.16 (p. 307). The number of minutes per day each student used a laptop for taking notes was recorded, with the following results:  = 13.2, s = 19.5.
a. Find and interpret a 95% confidence interval for the variance in the amount of time per day laptops are used for taking notes for all middle school students across the country.
b. Recall that in Exercise 2.100b you concluded that the distribution of laptop usage for taking notes cannot be normally distributed. Does this compromise the validity of the interval estimate, part a? Explain.Exercise 7.16
Laptop use in middle school. Refer to the American Secondary Education (Fall 2009) study of middle school students’ usage of laptop computers, Exercise 2.98 (p. 72). Recall that for a sample of 106 students, the researchers reported the following statistics on how many minutes per day each student used a laptop for taking notes:  = 13.2, s = 19.5 . Now the researchers want to estimate the average amount of time per day laptops are used for taking notes for all middle school students across the country.
a. Define the target parameter for the researchers in words and symbols.
b. In Exercise 2.100 a, you computed the interval,  ± 2s. Explain why this formula should not be used as an interval estimate for the target parameter.
c. Calculate a 90% confidence interval for the target parameter. Interpret the result.
d. Explain what the phrase “90% confidence” implies in your answer to part c.
e. In Exercise 2.100 b you concluded that the distribution of laptop usage for taking notes for the sample of 106 students cannot be symmetric. Consequently, the distribution cannot be normal. Does this compromise the validity of the interval estimate, part c? Explain.
Exercise 2.98
Motivation of drug dealers. Researchers at Georgia State University investigated the personality characteristics of drug dealers in order to shed light on their motivation for participating in the illegal drug market ( Applied Psychology in Criminal Justice , Sept. 2009). The sample consisted of 100 convicted drug dealers who attended a court-mandated counseling program. Each dealer was scored on the Wanting Recognition (WR) Scale, which provides a quantitative measure of a person’s level of need for approval and sensitivity to social situations. (Higher scores indicate a greater need for approval.) The sample of drug dealers had a mean WR score of 39, with a standard deviation of 6. Assume the distribution of WR scores for drug dealers is mound shaped and symmetric.
a. Give a range of WR scores that will contain about 95% of the scores in the drug dealer sample.
b. What proportion of the drug dealers will have WR scores above 51?
c. Give a range of WR sores that will contain nearly all the scores in the drug dealer sample.
Exercise 2.100b
Laptop use in middle school. Many middle schools have initiated a program that provides every student with a free laptop (notebook) computer. Student usage of laptops at a middle school that participates in the initiative was investigated in American Secondary Education (Fall 2009). In a sample of 106 students, the researchers reported the following statistics on how many minutes per day each student used his or her laptop for taking notes:  = 13.2, s = 19.5
b. Explain why the distribution of laptop usage for taking notes for these 106 students cannot be symmetric.