Data Analysis
A real estate agent, working entirely on commission, weekly makes an average of $850 with a standard deviation of $260 selling property in the city and an average of $1,340 with a standard deviation of $390 selling property in the suburbs. Assuming independence of what she sells in the two locations, this is the mean and standard deviation of her total weekly sales.
What is Mean= $2,190 and standard deviation= $469
A company wishes to survey what people think about a new product it plans to market. They decide to randomly sample from their customer database as this includes phone numbers and addresses. This procedure is an example of ________ sampling.
What is convenience?
Suppose that the probabilities that an answer can be found on Google is .95, on Answers.com is .92, and on both websites is .874. Are the possibilities of finding the answer on the two websites independent?
What is yes, because (.95)(.92)=.874?
In a one-sided hypothesis test for the mean, for a random sample of size 15 the t-score of the sample mean is 2.615. This is significant at the 5 percent level (true/false)
What is true?
It is estimated that females represent 25 percent of those people employed in computer systems design. Every week for one year, a government economist picks an SRS of 40 computer systems design employees and records the number of women. This theoretical distribution describes this procedure.
What is a binomial distribution with n=40 and p=.25?
If ten executives have salaries of $80,000, six have salaries of $75,000, and three have salaries of $70,000, this is the median salary.
What is $80,000?
In a study of Parkinson's disease, 100 volunteers had incisions made through their skulls. The patients were randomly sorted into two groups, one of which had a new drug inserted into the brain. In the other group, the skulls were closed with no treatment given. The patients did not know who received the drug. In the weeks to follow all 100 volunteers showed similar improvement in physical condition. This is an example of ____________.
What is the placebo effect?
Suppose 80% of jurors come to a just decision. In a jury of six people, this is the probability more than half come to a just decision.
What is .90112?
This is the critical t-value for finding a 96 percent confidence interval estimate from a sample of 18 observations.
What is 2.224?
There are two games involving flipping a fair coin. In the first game, you win a prize if you can throw between 45 percent and 55 percent heads. In the second game, you win if you can throw more than 60 percent heads. For each game, this is the choice you would make between 20 coin flips and 40 coin flips.
What is 40 times for the first game and 20 times for the second?
If every man married a woman who was exactly 3 years younger than he, this would be the correlation between the ages of married men and women.
What is 1?
This is the most useful procedure in establishing cause-and-effect relationships.
What is a controlled experiment?
Fifty-three percent of adults say they have trouble sleeping. If a doctor contacts an SRS of 85 adults, this is the probability that over 55% will say they have trouble sleeping. (Hint - think sampling distribution)
What is .3558?
A guidance counselor wishes to determine the mean number of changes in academic major by college students to within +/- 0.1 at a 90 percent confidence level. This sample size should be chosen if it is known that the standard deviation is 0.45.
What is 55?
A guidance counselor hands out a questionnaire about drug use to students whom she feel represent a cross section of the high school population, and asks the students to deposit the completed questionnaires in a box near the building front door at the end of the day. Of the following concerns, these are valid. ("None" and "all" can be a response.)
Concerns: issues from a convenience sample, issues from a voluntary response sample, response bias, nonresponse bias, undercoverage bias
What is issues from voluntary response sample and nonresponse bias?
A teacher is teaching two AP Statistics classes. On the final exam, the 25 students in the first class averaged 87, while the 30 student in the second class average a 98. If the teacher combines the classes, this will the average final exam score be.
What is 93?
You wish to survey people who have brought their cars for service during the past month. You decide to divide the city into 4 quadrants and pick a random sample of customers from stations in each quadrant who had work done during the past month. This procedure is an example of __________ sampling.
What is stratified random sampling?
There are five outcomes to an experiment and a student calculates the respective probabilities of the outcomes to be .34, .50, .42, 0, and -.26. This is the proper conclusion based on the student's data.
What is the student made an error?
The school superintendent wants to know what percentage of property owners are willing to support an increase in school taxes. This size sample should be obtained to determine with 90 percent confidence the support level to within 5 percent.
What is 271?
Two of the conditions to be checked for hypothesis tests of a population proportion or mean are a random sample and that sample is less than 10 percent of the population. Checking these conditions establishes this important criteria for each individual in the sample.
What is independence?
Suppose the correlation between two variables is r= .28. This will be the new correlation if .17 is added to all values of the x-variable, every value of the y-variable is doubled, and the two variables are interchanged?
What is .28?
A candy manufacturer wants to test consistency of the sugar content of the chocolate covered cherries produced in one factory. The company decides to randomly select three boxes of chocolate covered cherries from each day's production run of the factory and analyze every cherry in each of these boxes as to sugar content. This type of sampling is called __________.
What is cluster sampling?
Box A has four $10 bills and a single $100 bill, box B has 400 $10 bills and 100 $100 bills, and box C has 28 $1 bills. You can have all of box C or blindly pick one bill out of either box A or box B. This choice offers the greatest expected winning.
What is they all offer the same expected winning?
A researcher believes that a new diet should improve weight gain in laboratory mice. If the average gain for 12 mice on the new diet is 5.3 ounces with a standard deviation of 0.5 ounces, while 15 control mice on the old diet gain an average of 5 ounces with a standard deviation of 0.4 ounces, this is the p-value.
What is 0.0529?
A company bids on three independent contracts with probabilities of winning the contracts .1, .25, and .3, respectively. This is the probability of winning at least one contract.
What is .5275?