Math 159 classwork 1.3 and 1.4 Name: 1) Given the frequency distribution below: Height (in.) freq. a) What is the class width? 50 - 54 2 55 - 59 b) What are all the lower-class limits? W 60 - 64 c) What are all the class midpoints? 65 - 69 10 70 - 74 e) What is the total number of subjects in the data? 2) Construct relative frequency and cumulative frequency for the Grouped Frequency Distribution Table (GFDT) below. Round relative frequency and cumulative frequency to 3 decimal places. Age (yr) of best actress Rel.frequency Age Cumulative frequency when oscar was won Frequency (decimal) 20 - 29 29 less than 30 - 39 34 40 - 49 14 50 - 59 3 60 - 69 5 70 - 79 80 - 89 Use the grouped frequency table to answer the following questions. a) What percent of actress is greater than or equal to 40 years when they won Oscar? b) What percent of actress is between 50 to 69 years old when they won Oscar? c) What percent of actress is less than 50 years old when they won Oscar? 3) A researcher gather data on hours of video games played by school-aged children and young adults. The data are summarized in GFDT below: Hours Frequency Re. frequency Cumulative a) Calculate the relative and cumulative frequencies for (decimal) frequency each class. Round to 3 decimal places. 0-2 26 2-4 30 b) What percent of children play 6 or more hours of video 4-6 49 games? 6 -8 25 8 - 10 12 c) What percent of children play between 2 to 10 hours of 10 - 12 8 video games? 4) Determine if the following study is an observational study or an experiment. a) Study of salaries of college professors in California. College professors are surveyed. b) Study of effect of a new fertilizer on a soybean crop. New fertilizer is given to selected group of soybean farmers. c) Study of effect of vitamin C on colds. Data are obtained by randomly survey adults who attend a health conference. d) Study of effect of vitamin C on colds. Adults are randomly assigned to take vitamin C or a placebo.5) You plan to conduct an experiment to test the effectiveness of Sleepeze, a new drug that is supposed to reduce insomnia. 20 patients are selected and randomly divided into 2 groups. The first group receives Sleepeze and the second group a placebo. The patients do not know which group they are in but the nurse who passes out the pills know. a) Which group is the treatment group? b) Is there a control group? Which group is the control group? c) Is the study blind, double blind or neither? d) This study can best be described as: (circle one) controlled experiment/observational survey/ Experiment with no control e) What is the explanatory variable? f) What is the response variable? 6) A study of 2500 people who live in urban and another 2500 people who live in rural area shows that people who live in urban area have a higher average blood pressure. i) Does the result show that moving to rural area will result in lower blood pressure? (select all that apply.) a) Yes, the study shows that living in rural area causes lower blood pressure for residents. b) No, because this is an observational study, the result is show association only. ii) What could be a lurking variable that affect both blood pressure and choice of living in urban and rural. 7) Participants in a study are told that the new medication being tested is highly promising, but they are not told that only a small portion of participants will receive the new medication. Others will receive placebo treatments and traditional treatments. What is the issue with this study? (Select one.) a) Potential violations of the rule requiring informed consent. b) Participants privacy are not protected. c) Participants are exposed to high risk that outweighs any potential benefits