Midterm Exam 1 Review Questions (Answer Key) Chapter 1 1. Consumer Reports announced the average gas mileage of the top selling mini-vans for each U.S. car manufacturer. They used data from a sample of 50 vehicles to create their report. a) What are the observational units in this study? Each mini-van is an observational unit. b) Is the variable “average gas mileage” a categorical or quantitative variable? quantitative c) Is the variable “average gas mileage” a discrete or continuous variable? continuous 2. For each of the following statements determine if the underlined numerical values represents a parameter or a statistic. a) A study of 6076 adults in public restrooms (in Atlanta, Chicago, New York City and San Francisco) found that 23% did not wash their hands before exiting. statistic b) In a poll of all 2000 students at a high school it was found that 94% owned a cell phone. parameter c) Ty Cobb is one of Major League Baseball’s greatest hitters of all time with a career batting average of 0.366. parameter d) In a survey of 1011 people age 50 or older, 73% agreed with the statement “I believe in life after death.” statistic 3. In a Gallup News Service survey, 1017 randomly selected American adults aged 18 years or over were asked, “Of every tax dollar that goes to the federal government, how many cents of each dollar would they say are wasted?” Of the 1017 individuals surveyed, 35% indicated that 51 cents or more is wasted. Gallup poll reported that 35% of all adult Americans 18 years or older believe the federal government wastes at least 51 cents of each dollar spent. a) What is the population? All American adults aged 18 years or over b) What is the sample? 1017 selected American adults aged 18 years or over c) Which sampling method is used? (CIRCLE ONE) Cluster Multi-Stage Simple Random Stratified Systematic d) Is this an Observational Study or Experiment? (CIRCLE ONE) 4. A manager at Fresh Market wants to conduct a study regarding the shopping habits of her customers. She selects the first 60 customers who enter her store on a Saturday morning. a) What type of bias exists here? Sampling bias due to convenience sampling b) How could bias be affecting the results of the study? Saturday morning shoppers may have different shopping habits than those who come in at other times of the day or week. c) How could you improve the sampling method? Example: Randomly choose 5 shoppers each hour of each day throughout the week. Chapter 2 5. A statistics professor runs a hypothesis test to see if the proportion of times a player chooses “scissors” in the game Rock, Paper, Scissors is less than 1/3. The hypotheses tested are H
0
: p = 1/3 versus H
A
: p < 1/3. Would the following conclusions be a Type I Error, a Type II Error, or a correct decision? a) Conclude that the proportion is less than 1/3 when it actually equals 1/3. (Circle one) TYPE I ERROR TYPE II ERROR CORRECT DECISION b) Conclude that the proportion is less than 1/3 when it actually is less than 1/3. (Circle one) TYPE I ERROR TYPE II ERROR CORRECT DECISION c) Do not conclude that the proportion is less than 1/3 when it actually equals 1/3. (Circle one) TYPE I ERROR TYPE II ERROR CORRECT DECISION d) Do not conclude that the proportion is less than 1/3 when it actually is less than 1/3. (Circle one) TYPE I ERROR TYPE II ERROR CORRECT DECISION