Chapter 19 Practice Problems:

  1. A psychologist wants to know if adults with normal vision can be fooled by a certain optical illusion. She recruits 50 students from her PSY 120 class and finds that 42 of them are fooled by the illusion. (2 points each)

a)The sample population is?

b)The sample is?

c)The target population is?

  1. In a national survey on substance abuse, 10.0% of respondents aged 12 to 17 reported using illicit drugs within the past month.
  2. What is the population?
  • What is the parameter?
  • Is the number 10.0% a statistic or parameter? Why?
  • Is there any sampling error?
  1. An administrator at UVU is interested in the average age of students enrolled full-time at the university. She contacts the registrar’s office and obtain a spreadsheet of all full-time students with their date of birth.
  2. What is the population? What is the sample?
  • Is there any sampling error?
  1. The Denver Police Department wants to know if Hispanic residents of Denver believe that the police use racial profiling when making traffic stops. The police department takes a SRS of 200 addresses in a predominantly Hispanic neighborhood, and sends a uniformed Hispanic police officer to each address to ask questions of the adult living there. 25% of respondents indicated that they felt the department does use racial profiling when making traffic stops. Do you think the real percent of Hispanic residents that believe the DPD uses racial profiling is more than 25%, less 25%, or about 25%? Explain.
  1. One study on math education states that 28% of high school graduates are calculus-ready as freshman. This estimate was based on high schools in Salt Lake and Utah counties. Is it trustworthy? Explain.
  1. Sale of eggs that are contaminated with salmonella can cause food poisoning among consumers. A large egg producer takes an SRS of 200 eggs from all the eggs shipped in one day. The laboratory reports that 9 of these eggs had salmonella contamination. Unknown to the producer, 0.1% (one-tenth of one percent) of all eggs shipped had salmonella.

In this situation,

A)0.1% is a parameter and 9 is a statistic.

B)9 is a parameter and 0.1% is a statistic.

C)both 0.1% and 9 are parameters.

D)both 0.1% and 9 are statistics.

  1. A survey is carried out at a local high school to determine the percentage of students that have consumed alcohol.
  2. What is the population?
  • What is the parameter?
  1. A Census Bureau report on the income of Americans says that the median income of all California households in 2015 was $77,484. Suppose that many of the households asked their income by the Census Bureau give an answer that is too low because they fear that their answer will go to the Internal Revenue Service. This is an example of

A)Selection bias.

B)Non response bias.

C)Response bias.

D)Chance error.

  1. A city mayor sends out a survey to 500 randomly selected residents asking for their opinion on the new one-way streets in the downtown area. Of the 150 that responded, 100 were against the new traffic pattern in the downtown area. The actual estimated percent of residents against the new traffic pattern in the downtown area is probably more than 2/3, less than 2/3, or about 2/3? Explain.
  1. Dear Abby asks her readers the question, “If you could do it all over again, would you still have kids?” Of those that responded, 70% indicated they would not have kids at all. Do you think the real percent of parents that wouldn’t have kids if they could do it all over again is more than 70%, less than 70%, or about 70%? Explain.
  1. A UVU administrator would like to survey the student body on their opinions regarding higher student fees for an expanded intramural program. An interviewer is told to talk to:
  2. 25 white people, 4 Hispanics, and one black
  3. 15 males, and 15 females
  4. 24 under age 25, and 6 over age 25
  5. 15 paying over $800 a month in rent, and 15 paying less than $800 a month in rent.

The administrator states that this will give excellent results because the sample will match the student population on the demographic variables: age, gender, ethnicity, and socioeconomic status. Is this statement true or false? Explain.

  1. A survey organization would like to find out what percent of the American public is in favor of campaign finance reform. They pose the question “Do believe that private interest groups should be able to contribute exorbitant sums of money to the candidate of their choice? Yes or No.” They receive 85% responses of No. Do you think the actual percent of Americans that are in favor of campaign finance reform is more than 85%, less than 85%, or about 85%? Explain.