1.      A recent survey of local cell phone retailers showed that of all cell phones sold last month, 64% had a camera, 28% had a music player and 22% had both. Which of the following statements about cell phones sold last month is true?

4 points   

QUESTION 2

1.      The number of male babies in a sample of 10 randomly chosen babies is a:

4 points   

QUESTION 3

1.      Thirty work orders are selected from a filing cabinet containing 500 work order folders by choosing every 15th folder. Which sampling method is this?

4 points   

QUESTION 4

1.      A sample of 250 people resulted in a confidence interval estimate for the proportion of people who believe that the federal government’s proposed tax increase is justified is between 0.14 and 0.20. Based on this information, what was the confidence level used in this estimation?

4 points   

QUESTION 5

1.      A 99% confidence interval estimate can be interpreted to mean that

4 points   

QUESTION 6

1.      At the U.S. Open Tennis Championship a statistician keeps track of every serve that a player hits during the tournament. The statistician reported that the mean serve speed of a particular player was 105 miles per hour (mph) and the standard deviation of the serve speeds was 9 mph. If nothing is known about the shape of the distribution, give an interval that will contain the speeds of at least eight-ninths of the player’s serves.

4 points   

QUESTION 7

1.      Chebychev’s Theorem:

4 points   

QUESTION 8

1.       A major department store chain is interested in estimating the average amount its credit card customers spent on their first visit to the chain’s new store in the mall. Fifteen credit card accounts were randomly sampled and analyzed with the following results: X (i.e. Xbar = $50.50) and s₂(i.e. s squared = 400). Assuming the distribution of the amount spent on their first visit is approximately normal, what is the shape of the sampling distribution of the sample mean that will be used to create the desired confidence interval for μ (mew)?

4 points   

QUESTION 9

1.      As part of an economics class project, students were asked to randomly select 500 New York Stock Exchange (NYSE) stocks from the Wall Street Journal. As part of the project, students were asked to summarize the current prices (also referred to as the closing price of the stock for a particular trading date) of the collected stocks using graphical and numerical techniques. Identify the sample of interest for this study.

4 points   

QUESTION 10

1.      A standardized test has a mean score of 500 points with a standard deviation of 100 points. Five students’ scores are shown below.

 
Which of the students have scores within two standard deviations of the mean?

4 points   

QUESTION 11

1.       Suppose a sample of n = 50 items is drawn from a population of manufactured products and the weight, X, of each item is recorded. Prior experience has shown that the weight has a probability distribution with μ = 6 ounces (mew = 6 ounces) and σ = 2.5 ounces (sigma = 2.5 ounces). Which of the following is true about the sampling distribution of the sample mean if a sample of size 15 is selected?

4 points   

QUESTION 12

1.      A probability distribution is an equation that

4 points   

QUESTION 13

1.      A survey was conducted to determine how people feel about the quality of programming available on television. Respondents were asked to rate the overall quality from 0 (no quality at all) to 100 (extremely good quality). The stem-and-leaf display of the data is shown below.

 
What percentage of the respondents rated overall television quality as very good (regarded as ratings of 80 and above)?

4 points   

QUESTION 14

1.      A statistics professor wanted to test whether the grades on a statistics test were the same for upper and lower classmen. The professor took a random sample of size 10 from each, conducted a test and found out that the variances were equal. For this situation, the professor should use a t test with independent samples.

  True

  False

4 points   

QUESTION 15

1.      At a computer manufacturing company, the actual size of computer chips is normally distributed with a mean of 1 centimeter and a standard deviation of 0.1 centimeter. A random sample of 12 computer chips is taken. What is the standard error for the sample mean?

4 points   

QUESTION 16

1.      Which display is most likely to reveal association between X and Y?

4 points   

QUESTION 17

1.       During its grand opening week, Stickler’s bicycle shop offers a “wheel of discount savings.” After customers select the items they wish to purchase, they spin the wheel to determine the discount they will receive. The wheel is divided into 12 slices. Six slices are red and award a 10% discount, three slices are white and award a 20% discount, and two slices are blue and award a 40% discount. The remaining slice is gold and awards a 100% discount!  The probability that a customer gets at least a 40% discount is

4 points   

QUESTION 18

1.      Which model would you use to describe the probability that a call-center operator will make the first sale on the third call, assuming a constant probability of making a sale?

4 points   

QUESTION 19

1.      The amount spent on textbooks for the fall term was recorded for a sample of five university students – $400, $350, $600, $525, and $450. Calculate the value of the sample standard deviation for the data.

4 points   

QUESTION 20

1.      Suppose the ages of students in Statistics 101 follow a skewed-right distribution with a mean of 23 years and a standard deviation of 3 years. If we randomly sampled 100 students, which of the following statements about the sampling distribution of the sample mean age is incorrect?

4 points   

QUESTION 21

1.      A die is rolled. If it rolls to a 1, 2, or 3 you win $2. If it rolls to a 4, 5, or 6 you lose $1. Find the expected winnings.

4 points   

QUESTION 22

1.      What type of probability distribution will the consulting firm most likely employ to analyze the insurance claims in the following problem? An insurance company has called a consulting firm to determine if the company has an unusually high number of false insurance claims. It is known that the industry proportion for false claims is 3%. The consulting firm has decided to randomly and independently sample 100 of the company’s insurance claims. They believe the number of these 100 that are false will yield the information the company desires.

4 points   

QUESTION 23

1.      If we are testing for the difference between the means of 2 independent populations presuming equal variances with samples of n₁ = 20 (i.e. n1 = 20) and n₂ = 20 (i.e. n2 = 20), the number of degrees of freedom is equal to

4 points   

QUESTION 24

1.      The option to buy extended warranties is commonplace with most electronics purchases. But does the type of purchase affect a consumer’s willingness to pay extra for an extended warranty? Data for 420 consumers who purchased digital cameras and laptop computers from a leading electronics retailer are summarized in the table. The probability that a consumer does not purchase an extended warranty is

2. 

4 points   

QUESTION 25

1.      The amount of television viewed by today’s youth is of primary concern to Parents Against Watching Television (PAWT). 300 parents of elementary school-aged children were asked to estimate the number of hours per week that their child watches television. The mean and the standard deviation for their responses were 17 and 3, respectively. PAWT constructed a stem-and-leaf display for the data that showed that the distribution of times was a symmetric, mound-shaped distribution. Give an interval where you believe approximately 95% of the television viewing times fell in the distribution.

4 points   

QUESTION 26

1.      Consider the following data: 6, 7, 17, 51, 3, 17, 23, and 69. The range and the median are:

4 points   

QUESTION 27

1.      For quality control purposes, a company that manufactures copper sheets routinely takes samples from its production process. Since its product is often used for decorative purposes, one inspection check involves counting the number of imperfections or flaws on sheets that measure 36 sq. ft. Suppose the average number of imperfections per sheet of this size is 3. What is the probability that a sheet of this size has 2 imperfections?

4 points   

QUESTION 28

1.      The standard error of the mean

4 points   

QUESTION 29

1.      Suppose that incoming calls per hour to a customer service center of a small credit union are uniformly distributed between 0 and 6 calls. The probability that fewer than 3 calls are received per hour is

4 points   

QUESTION 30

1.      If the outcomes of a random variable follow a Poisson distribution, then their

4 points   

QUESTION 31

1.      Parking at a university has become a problem. University administrators are interested in determining the average time it takes a student to find a parking spot. An administrator inconspicuously followed 270 students and recorded how long it took each of them to find a parking spot. Identify the variable of interest to the university administration.

4 points   

QUESTION 32

1.      What number is missing from the table?

4 points   

QUESTION 33

1.      The t test for the difference between the means of 2 independent populations assumes that the respective

4 points   

QUESTION 34

1.      Temperature in degrees Fahrenheit is an example of a(n) __________ variable.

4 points   

QUESTION 35

1.      The amount of television viewed by today’s youth is of primary concern to Parents Against Watching Television (PAWT). 330 parents of elementary school-aged children were asked to estimate the number of hours per week that their child watches television. Identify how the data were collected in this study.